Removing multiple contacts accidentally added to another list

Hello!

I have multiple contacts on list A, and multiple different contacts on list B.

List A was accidentally added to list B.

Is there a way to identify, as a group, list A in the new larger list B, and separate them back out from list B?

I know I can go through them one by one, but there are 1000s of contacts I'd have to go through.

Possible to do them as a group?

Thank you!