How to delete multiple conversations in imessage at once?

I have attempted to follow the instructions I could find, like using the shift key or control key or command key. Even the Select All option under Messages => Edit is grayed out. Was this an oversight in the Big Sur release? If so, we need either a defect or RFE A.S.A.P.

This was a HUGE oversight. It's a pain to delete messages when it takes three seperate actions (swipe, click, click) to delete a message. I'm trying to clean out my iMessage bin and there are over 200 messages.

Yes. Nothing works! Why was this not included in the update?!!