removing visa stickers (i.e. the steam iron trick)?
As mentioned, they peel right off and do come loose after a couple of years. Just make sure they are stapled to the last page of your passport. What you don't want to do is loose those (expired) visas.
I've done this and in fact I think it was US immigration that affixed the loose visas. Used the passport about 100 times after that, never an issue.