return error if option not set instead of soft delete (#15030)

i18n/en.json

@@ -2618,6 +2618,10 @@
     "id": "api.user.create_user.signup_link_invalid.app_error",
     "translation": "The signup link does not appear to be valid."
   },
+  {
+    "id": "api.user.delete_team.not_enabled.app_error",
+    "translation": "Permanent team deletion feature is not enabled. Please contact your System Administrator."
+  },
   {
     "id": "api.user.demote_user_to_guest.already_guest.app_error",
     "translation": "Unable to convert the user to guest because is already a guest."