I would just stop talking to her and say you are not interested. There used to be a lot of my sisters' friends after me. Some of them, one in particular, was her friend just to get to me. I was nice to her, but I didn't like her at all and she kept bugging me, because she thought I liked her because I was nice to her. Actually she still asks my sister about me often, since they happen to work in the same place and it's been years now. A couple of my sisters' friends that liked me were kind of hot though and I wish I wasn't shy. So just say you are not interested if you truly aren't and/or don't talk to her or she might keep bothering you. Save her and yourself some time.