How do I remove old transactions that are from 10 years ago that are coming up on my screen when I am trying to reconcile my monthly statements?

Don't do it, if you remove or void a transaction in the past, all balances in that account from then until now will change.

And of course it also changes the audit trail in the event of an audit.

As for why they show up all of a sudden, sorry I can not help, but it sounds like yet another new bug in the software