Well, see you take them out at night in a dark alley, (make sure you have an alibi) and tell them to look in the dumpster, and then you *makes*stabbing*and/or*shooting*noise* while they're looking. Then push the body in! And that is how you dump a friend! =D I'm kidding of course. I don't think you should get rid of a friend if it's at all possible to avoid it. It's one of the most heartbreaking things that can happen to a person. Please don't just stop talking to them. I've had this happen to me before, my best friend. It was pretty cold when I finally saw her after six months and she said "oh, sorry. I been busy". Trust me, it's a lot less painful to just come right out and say it.
If you cant express verbally why you dont want to be friends anymore, do it with actions. Start hanging out places your friend will not or cannot go. Dont return calls/texts promptly or at all. The less desireable you are as a friend the better. This friend will eventually get the point or just decide on his/her own that perhaps they dont like you as much as they used to!
She isn't your friend. Just be honest and stop hanging out. Just because you don't like her, doesn't mean she isn't a person with feelings. It's not healthy for her to be around you with this attitude anyway.
Pick a fight with them over something stupid. Prank them and then make sure they are to scared to come near you, or do what I did, do something they hate then talk about it forever until they want to leave you in a dark alley.