I have so far experienced wonderful results with weight training, especially my butt area. However, I do want to reduce the amount of weight training I do to only my glutes.

I basically want to lose 10 pounds, and I'm going to eat well and do lots of cardio, and only weight train my butt because I only want that portion of my body to get more muscular.

I know you cant spot reduce, but can you spot train? By reduce I mean be overweight and workout abs thinking you'll get a flat belly. By spot train I mean doing cardio and only working out my butt so it gets more muscular while I lose body fat through my cardio.

I'm not an expert, but I think you can spot "train", however I wouldn't give up training the whole body, just do more for the area you want more muscle, give it extra attention like more weight/sets or even one extra day a week of just training that part.....but don't sacrifice the rest.

Yes, you can definitely "spot train". Basically, you focus on one group of muscles and work them as hard as you can.
Of course, it is usually a very good idea to spend at least some time on the other muscles. It is really of benefit to you to train muscles evenly because when one muscle group is much stonger than another it causes an imbalance (with the weaker muscles ) which can sometimes lead to injuries.