Delete the number or email address. If you really don't feel you can do that, I changed my ex's name in my phone, I can't tell you what I changed it to as children come on this site! but needless to say after a few drinks, I'd go to text him, not be able to find his number, remember that I'd changed it to *expletive* and remember why he was called that! took the urge off wanting to ring him. on another occassion I changed his name to "Do not call when drunk" or it he's done something awful in the past, cheated, druggie, or anything that you don't like him for, change it to that and you'll remember why he's an ex!!!!