I added about 175 users into the wrong group in our SharePoint site. Is it possible to "undo" the action? The bigger challenge is that I did not make a list of the existing members before adding the new ones. It's not the end of the world to recreate the original member list; I know who created the original, but I'd rather not have to compile a 2nd list if possible.
This is hosted on our internal network, but do not know which version we are using or how to find it.