Is there a good way of denying someone on Facebook or is it okay to be a jerk?

I am not that into Facebook, I’m more of a Twitter guy, and as such I only check my Facebook account once a week or less and reserve it mostly for family and close friends. The other day I checked my account and found that I had received a friend invite and comment on my account from a girl I dated many years ago. The comment she left wasn’t anything big, just a quick “hi, how are you?” but the thing is I have no interest of talking to her at all.

Is there a polite way of telling her to F’ Off? or am I better off just ignoring her and declining her friend request.