Hey, this isn’t a bug. In the new Agents window, the Delete option was intentionally replaced with Archive so you don’t accidentally lose your chat history. So right click → Archive is the way to remove a chat from the active list. You can restore archived chats later.
If you need a permanent Delete, it’s still available in the chat history dropdown in the regular IDE editor window, not in the Agents window sidebar.
If you want Delete back in the Agents window, there’s an open feature request you can vote on: Allow single click deleting chats from chat history panel and Agent Side Bar
Let me know if you can’t find anything.