Where to request ACH Direct DEBIT of funds from MY OWN personal bank account?
Call Wells Fargo or go to a branch.  Tell them what you're trying to accomplish, not the vehicle you think you should use to get there.  Don't tell them you want to ACH DEBIT from YOUR ACCOUNT of YOUR MONEY.  Tell them you apparently need a paperless transaction sent to this and that account at this and that bank.  See if they offer a solution.