diff --git a/README.md b/README.md
index b4f1c56..b7b2dff 100644
--- a/README.md
+++ b/README.md
@@ -204,7 +204,7 @@ mailtrap domains list --output text
 | **Permissions** | `permissions resources`, `permissions bulk-update` |
 | **Tokens** | `tokens list`, `tokens get`, `tokens create [--expires-at]`, `tokens delete`, `tokens reset [--expires-at]` |
 | **Billing** | `billing usage` |
-| **Organizations** | `organizations list-sub-accounts`, `organizations create-sub-account` |
+| **Organizations** | `organizations list-sub-accounts`, `organizations create-sub-account`, `organizations delete-sub-account` |
 | **Config** | `configure`, `completion [bash\|zsh\|fish\|powershell]` |
 
 ## Shell Completion
diff --git a/docs/TEST_PLAN.md b/docs/TEST_PLAN.md
index 74e558e..b10b31e 100644
--- a/docs/TEST_PLAN.md
+++ b/docs/TEST_PLAN.md
@@ -325,8 +325,9 @@ Prerequisite: Send an email with an attachment to the sandbox.
 | 20.1 | List sub-accounts | `mailtrap organizations list-sub-accounts` | Table with sub-accounts |
 | 20.2 | Create sub-account | `mailtrap organizations create-sub-account --name "test-sub"` | New sub-account |
 | 20.3 | Missing name | `mailtrap organizations create-sub-account` | Error: `--name is required` |
+| 20.4 | Delete sub-account | `mailtrap organizations delete-sub-account --org-id <ORG_ID> --sub-account-id <NEW_ID>` | Success message; repeated call returns 404 |
 
-**Caution:** Creating sub-accounts may have billing implications.
+**Caution:** Creating sub-accounts may have billing implications. Deleting a sub-account is permanent and removes all of its data; deleting the organization's last sub-account also deletes the organization. Only delete the sub-account created in 20.2.
 
 ## 21. Configure
 
@@ -401,7 +402,7 @@ Run tests in dependency order so earlier tests create resources needed by later
 17. **Permissions** (read/update)
 18. **Tokens** (CRUD — may need admin token)
 19. **Billing** (read-only)
-20. **Organizations** (read-only, skip create unless safe)
+20. **Organizations** (read-only, skip create/delete unless safe – delete only the sub-account created in 20.2)
 21. **Configure** (local config only)
 22. **Inbound** (CRUD for folders/inboxes; messages/threads need received mail)
 
@@ -430,6 +431,6 @@ Run tests in dependency order so earlier tests create resources needed by later
 | Permissions | 2 | 3 |
 | Tokens | 5 | 6 |
 | Billing | 1 | 2 |
-| Organizations | 2 | 3 |
+| Organizations | 3 | 4 |
 | Configure | 1 | 2 |
-| **Total** | **~90** | **~107** |
+| **Total** | **~91** | **~108** |
diff --git a/internal/commands/organizations/delete_sub_account.go b/internal/commands/organizations/delete_sub_account.go
new file mode 100644
index 0000000..ac5fb15
--- /dev/null
+++ b/internal/commands/organizations/delete_sub_account.go
@@ -0,0 +1,54 @@
+package organizations
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/mailtrap/mailtrap-cli/internal/client"
+	"github.com/mailtrap/mailtrap-cli/internal/cmdutil"
+	"github.com/spf13/cobra"
+)
+
+func NewCmdDeleteSubAccount(f *cmdutil.Factory) *cobra.Command {
+	var orgID string
+	var subAccountID string
+
+	cmd := &cobra.Command{
+		Use:   "delete-sub-account",
+		Short: "Delete a sub-account from an organization",
+		Long: `Delete a sub-account from an organization. Requires sub-account management permissions for the organization.
+
+The deletion is permanent: the sub-account and all of its data are removed and cannot be restored.
+Deleting the organization's last sub-account also deletes the organization.
+
+A repeated call for the same sub-account returns 404. Rate limit: 10 requests per minute per organization.`,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if err := cmdutil.RequireFlag("org-id", orgID); err != nil {
+				return err
+			}
+			if err := cmdutil.RequireFlag("sub-account-id", subAccountID); err != nil {
+				return err
+			}
+
+			c, err := f.NewClient()
+			if err != nil {
+				return err
+			}
+
+			path := fmt.Sprintf("/api/organizations/%s/sub_accounts/%s", orgID, subAccountID)
+
+			if err := c.Delete(context.Background(), client.BaseGeneral, path, nil); err != nil {
+				return err
+			}
+
+			fmt.Fprintf(f.IOStreams.Out, "Sub-account %s deleted successfully\n", subAccountID)
+
+			return nil
+		},
+	}
+
+	cmd.Flags().StringVar(&orgID, "org-id", "", "Organization ID")
+	cmd.Flags().StringVar(&subAccountID, "sub-account-id", "", "Sub-account ID")
+
+	return cmd
+}
diff --git a/internal/commands/organizations/organizations.go b/internal/commands/organizations/organizations.go
index 5e8d4f0..0883765 100644
--- a/internal/commands/organizations/organizations.go
+++ b/internal/commands/organizations/organizations.go
@@ -13,6 +13,7 @@ func NewCmdOrganizations(f *cmdutil.Factory) *cobra.Command {
 
 	cmd.AddCommand(NewCmdListSubAccounts(f))
 	cmd.AddCommand(NewCmdCreateSubAccount(f))
+	cmd.AddCommand(NewCmdDeleteSubAccount(f))
 
 	return cmd
 }
diff --git a/internal/commands/organizations/organizations_test.go b/internal/commands/organizations/organizations_test.go
index 7ebdf1e..caf8b41 100644
--- a/internal/commands/organizations/organizations_test.go
+++ b/internal/commands/organizations/organizations_test.go
@@ -150,3 +150,51 @@ func TestCreateSubAccountMissingFlags(t *testing.T) {
 		t.Fatal("expected error when required flags are missing")
 	}
 }
+
+func TestDeleteSubAccount(t *testing.T) {
+	f, buf, cleanup := setupTest(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodDelete {
+			t.Errorf("expected DELETE, got %s", r.Method)
+		}
+		if !strings.HasSuffix(r.URL.Path, "/api/organizations/456/sub_accounts/789") {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+
+		w.WriteHeader(http.StatusNoContent)
+	})
+	defer cleanup()
+
+	cmd := organizations.NewCmdOrganizations(f)
+	cmd.SetArgs([]string{"delete-sub-account", "--org-id", "456", "--sub-account-id", "789"})
+	cmd.SetOut(buf)
+
+	err := cmd.Execute()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	output := buf.String()
+	if !strings.Contains(output, "Sub-account 789 deleted successfully") {
+		t.Errorf("expected output to contain 'Sub-account 789 deleted successfully', got:\n%s", output)
+	}
+}
+
+func TestDeleteSubAccountMissingFlags(t *testing.T) {
+	f, _, cleanup := setupTest(func(w http.ResponseWriter, r *http.Request) {})
+	defer cleanup()
+
+	buf := &bytes.Buffer{}
+	f.IOStreams.Out = buf
+
+	cmd := organizations.NewCmdOrganizations(f)
+	cmd.SetArgs([]string{"delete-sub-account", "--org-id", "456"})
+	cmd.SetOut(buf)
+
+	err := cmd.Execute()
+	if err == nil {
+		t.Fatal("expected error when --sub-account-id is missing")
+	}
+	if !strings.Contains(err.Error(), "--sub-account-id is required") {
+		t.Errorf("expected '--sub-account-id is required' error, got: %v", err)
+	}
+}
diff --git a/skill-evals/mailtrap-cli/evals.json b/skill-evals/mailtrap-cli/evals.json
index 333e1c8..9c4512e 100644
--- a/skill-evals/mailtrap-cli/evals.json
+++ b/skill-evals/mailtrap-cli/evals.json
@@ -170,6 +170,15 @@
       "must_not_contain": ["accounts", "list-sub-accounts"]
     }
   },
+  {
+    "name": "delete_sub_account",
+    "prompt": "Remove sub-account 12347 from organization 2000002",
+    "expected": {
+      "command": "organizations delete-sub-account",
+      "flags": ["--org-id", "--sub-account-id"],
+      "must_not_contain": ["accounts delete", "account-access remove", "list-sub-accounts"]
+    }
+  },
   {
     "name": "send_with_cc_bcc",
     "prompt": "Send a transactional email from boss@acme.com to team@acme.com, CC manager@acme.com, BCC hr@acme.com with subject 'Update'",
diff --git a/skills/mailtrap-cli/references/accounts.md b/skills/mailtrap-cli/references/accounts.md
index 7bc2730..05aae01 100644
--- a/skills/mailtrap-cli/references/accounts.md
+++ b/skills/mailtrap-cli/references/accounts.md
@@ -132,3 +132,16 @@ Create a sub-account under an organization.
 |------|------|----------|-------------|
 | `--org-id` | string | Yes | Organization ID |
 | `--name` | string | Yes | Sub-account name |
+
+---
+
+## organizations delete-sub-account
+
+Delete a sub-account from an organization. Requires sub-account management permissions for the organization.
+
+| Flag | Type | Required | Description |
+|------|------|----------|-------------|
+| `--org-id` | string | Yes | Organization ID |
+| `--sub-account-id` | string | Yes | Sub-account ID |
+
+**Caution:** Permanent – the sub-account and all of its data are removed and cannot be restored. Deleting the organization's last sub-account also deletes the organization. A repeated call for the same sub-account returns 404. Rate limit: 10 requests per minute per organization.