Removing tags

I am relatively new to Infusionsoft but I have been pushed in the deep end trying to maintain an established account when the previous account management team withdrew their service (and support) so excuse me if this is basic stuff.

One of the campaigns they set up wasn’t as the client wanted so I copied a sequence from a different campaign and moved the ‘remove tag’ bit to the end of the new sequence. That unexpectedly (to me) resulted in 3.3K of historical contacts entering the new sequence (receiving an email).

There are other emails in the sequence and I do not want anyone else to receive any more emails. I think I have removed the tag from them but the list of campaigns is still showing 3.3k active contacts.

Should the figure reduce instantly it’s done correctly and if the old suppliers are no longer willing to provide any support, where can I find a certified partner that will?