How to shake an old freind and gain a new!?

So say my freinds are A,B,C. A is the one i want to get rid of. B is a jock who I like and we play on the same softball team. C is nice and is way over empathetic once A and B were in the lunch line for a long time and she told me she was afraid that when she left them that they got killed by a hobo (weird IK.) I want to become freinds with D and A and D hate eachother! I dislike A very much she is so annoying! So how do i jump freinds?