I Fought the Lamp and the Lamp (almost) Won

A note: electricity is dangerous. Having worked in the theatre as both a light tech and a lighting designer, let me tell you that it's not good enough to just have a switch flipped off. You need to make sure there's no power going to the wires at all. This means switching it off at the fuse box or panel. After you've done this, DO NOT take the light fixture (in this case a ceiling fan) down by yourself whilst balancing on top of a ladder. I say this from a place of experience and warn you that they are heavier than they look. 

The only benefit to taking it down this way is you'll find out if you have a natural self-preservation instinct and how quick your reflexes are. This happened in my case as the weight of the fixture threatened to pull me off the ladder and down (head first) to the floor. Fortunately I allowed the fixture to drop before I went over. 

Now, after taking off a fixture, assuming you've survived this step, you must cap off the wires if you're not going to put another fixture up right away. Again, make sure to keep the power off, cut the wires back with wire cutters and cap them off by screwing the caps on. Give a little tug and... voila. 

safe wires.