Ok here is the problem. My brother left iPhone to go to android but everyone who uses iPhone who tries to txt him it goes to iMessage and we can not figure out how to turn that off so it forces it back txt message when other iPhone uses try to message him.
Take his old iPhone, remove the SIM, go to General > Erase All Content and Settings
If the iPhone is no longer in his/your posession, that's a big problem. There's another thread floating out there today about a guy who forgot to wipe his phone before handing it over to a buyer, with unpleasant consequences.
EDIT / If he ported his number, perhaps it will just take time to filter out from the carrier?