To delete your Grok chat history, go to grok.com/app and remove messages...

https://wiki-book.win/index.php/What_Should_I_Do_if_Grok_Delete_All_Doesn%E2%80%99t_Show_on_Mobile%3F

To delete your Grok chat history, go to grok.com/app and remove messages directly from the conversation. Don’t forget to check the Recently Deleted folder—it holds your deleted chats for 30 days before permanent removal