To delete your Grok chat history on grok.com/app and X, go to your chat...

https://domgodwinson38.gumroad.com/p/how-do-i-delete-files-from-grok-the-ones-people-forget-a-full-cleanup-guide

To delete your Grok chat history on grok.com/app and X, go to your chat settings and choose “Delete History.” Remember, this clears only chat messages—files and Imagine media must be deleted separately