Originally Posted by Duragrouch

Beat me to it (assuming correct tool to remove). Aluminum has a high coefficient of thermal expansion versus steel, and will expand to loosen the press fit at the taper. However, aluminum can lose its strength at a fairly low temp, and hot air transfers heat slower than water. Thus, I recommend boiling a small pot of water, and pour it over the crank at the tapers, or even better, turn the bike with that crank down and submerged in the pot, as it being aluminum, the heat will rapidly transfer away from the spindle end, but not if you submerge the whole crank arm for time enough to get it close to boiling water temp, which is still a safe temp for aluminum. This all assumes you are at less than a couple thousand feet above sea level, so the boiling temp is not reduced a lot.

Heat, applied with a soldering iron to a bolt, or heat gun for something like a bottom bracket, is also ideal for softening anaerobic thread locking adhesive ("Loctite"), for much easier disassembly.