Once you get admitted somewhere, you can perhaps talk to the faculty about skipping classes. You should have an advisor or set of advisors to talk to, and they

Once you get admitted somewhere, you can perhaps talk to the faculty about skipping classes. You should have an advisor or set of advisors to talk to, and they should help you get something out of your education, including skipping requirements for things you know. You'll have to do a certain number of credit hours either way, but you can perhaps avoid sitting through a lot of stuff you already know if you can convince them you know it and just don't want to waste the time (not just your advisor; they might have you talk to faculty who can evaluate you); you can, perhaps, skip to classes full of material you won't know, perhaps even graduate courses for credit as an undergraduate. You'd probably have to know the stuff you want to skip pretty well. Honestly, your advisor should work with you to make sure that you're not wasting your time at a minimum. If not, you can drop out of the program.