Q: how do you activate an erased iphone 5c when the previous owner cannot remember id or password

My husband is now using our son's old iPhone 5c, it glitched when updating froze at the apple screen and had to be reset. Our son does not remember the id or password he used to set up his Apple account. After what has felt like an eternity, I finally have it updated and running with my husbands new apple id and acct, however...I cannot get past the "Activation Lock" screen to get the phone functioning.   HELP!  PLEASE!!