inc folder, modify the file:

hooks.php comment out line 738 and set $can_delete to true by default

ajax.php comment out line 1900 and set $can_delete to true by default

After this modification, in the websocks version, each participant can clear the chat history, and other participants will not immediately be unable to see the chat history until they refresh the entire page.

I think this can be designed as a setting option:

Allow participants to clear the chat history.