diff --git a/pageindex/backend/cloud.py b/pageindex/backend/cloud.py
index 81c1cde..c44e892 100644
--- a/pageindex/backend/cloud.py
+++ b/pageindex/backend/cloud.py
@@ -205,13 +205,14 @@ class CloudBackend:
         except CollectionNotFoundError:
             return  # already gone — delete is idempotent
         if folder_id:
-            self._request("DELETE", f"/folder/{self._enc(folder_id)}/")
-            # Drop the cached id so a later same-name op re-resolves instead of
-            # reusing the now-deleted folder_id. Only when it was a REAL id —
-            # if folder_id was falsy, the cache holds the "folders unavailable
-            # on this plan" None sentinel, which must survive so we don't
-            # re-issue a doomed GET /folders/ on the next call.
-            self._folder_id_cache.pop(name, None)
+            # The cloud API has no folder-deletion endpoint (only POST /folder
+            # and GET /folders exist) — fail clearly instead of issuing a
+            # request that can only 404.
+            raise PageIndexError(
+                f"Deleting a cloud collection is not supported by the PageIndex "
+                f"API — delete folder '{name}' in the dashboard "
+                "(https://dash.pageindex.ai) instead."
+            )
 
     # ── Document management ───────────────────────────────────────────────