Many have disconnected or entirely removed their A/C units. These units can cost a pretty penny, so I'd suggest you keep together everything you remove in case you decide to reinstall at some future time.
Before you do anything, you should go to an A/C shop and have them evacuate your entire system so that no R-12 is released into the atmosphere. Of course, the system may already be empty.
The rest is relatively easy, depending on the degree to which you want to remove the system. The underdash unit is as simple as just disconnecting all the hoses and brackets so that the assembly can be removed.
If you decide to pull the hoses into the engine bay, you'll need something to plug the firewall grommet holes. Otherwise you could plug the dangling hoses and leave them under the dash.
You could also remove the compressor and hoses entirely, prompting the removal of the A/C belt. If you have a custom setup wherein the A/C belt drives something else, you'll need to create an alternate belt arrangement for this. I would suggest keeping with the factory arrangement: 1 belt for water pump and alternator, 1 belt for power-steering (if available), and 1 belt for just the A/C compressor. Certainly, one less belt driven off the engine would ease the engine load a bit.
The compressor sits below the alternator attached to an "elephant bracket" which may have an idler pulley or two. You could also remove this bracket, but it might involve removing more things around the front of the engine, and re-sealing any bolts unscrewed from the block, as some of these bolts enter water and/or oil passages in the block.
Lastly, you could remove the condenser and dryer assemblies near the radiator. This would allow more air to flow through the radiator and give better cooling.
So, it all depends on how far you want to go in removing the system. You can even do it in stages as you get more convinced you don't really want it.
