Do you just stop talking to them and ignore them from now on? Stop contacting them and if they contact you just ignore them or make excuses not to meet up?
I am ditching a friend as she's constantly unreliable and is very selfish, but I have to come into contact with her at times (ie school pick up) and we have mutual friends so I don't want to create bad feeling. She is still on my Facebook friends, obviously if I deleted her she would probably notice and be upset so I guess it's best to leave her on there and just not have any communication with her on there?
I have ditched friends before in the past but it's always ended up becoming nasty or causing a rift, I really want to avoid any of that hassle this time.