It seems highly unlikely that colleges will revoke your acceptance if you drop Spanish, but you would be wise to call and ask before you do. If you’re told, “No problema,” be sure that you write down (and save) the name of the person you spoke with, just in case you are questioned later on. (You can try making contact by email first, but you probably want a response quickly, so a phone call might be a better bet, although email gives you “written” proof of the verdict.) You should also contact any college where your decision is still pending.
College folks can be persnickety about students who finish the school year with a less rigorous course load than the one they applied with. So, although you’ll mostly likely be fine if you make this change, I can’t say for sure that every college that admitted you will be happy with it.