I have really "fat legs".. but it's not mostly fat that's in it.. I think it's mostly muscle.. and I don't know what to do with it.. I'm not a big person.. I'm not tall or have a big body built.. so it's just so totally out of proportion with the rest of my body parts.
And the only thing I like about the gym is the treadmill.. and I think it's making my legs bigger.. but it's the only equipment in the gym that's making me sweat.. the stationary bike is not making me sweat.
So my question is how can I slim fat legs aside from "not doing the treadmill anymore"?

Best bet is to start with yoga -- sign up for a class that meets once a week, and do the positions you've learned at home once or twice a day. Practice with being very smooth in how you transition from one position to another. Have New Age music playing in the background. Keep your mind quiet and focused on the yoga.

Why yoga? It stretches and elongates muscles. Do yoga exclusively for a month, then check on how your thighs look.