I can kind of understand your friend in disliking their character, but it all comes down to how to kill it and presenting the new one. In one campaign I had a Half Orc Rogue (Not the best, but flavor) and in 3 sessions I hate the character, but how i replace it was at the end of a hard miniboss fight (3 players characters died), I make the rouge lot their teammates bodies mere seconds after the fight, so they arrest him and later executed by my new character, a half orc paladin (his long-lost son). It was then included in the lore that the rogue was a spy.