How do I remove an aftermarket remote starter from a 1996 GMC Jimmy? I believe it is draining my battery, when we jumped the truck it started all by itself with no keys in ignition.

If factory alarm, lock drivers door with key, wait an hour should automatically reset, if it's a factory alarm and you have no keypad. Try removing the fuse for the alarm and wait a few minutes and replace fuse and see if it will reset the alarm.
If its an aftermarket alarm system, look under plastic panel below steering wheel for a plastic black box that is about the size of a deck of cards, izip tied or just hanging with a plugin with several different colored wires and unplug it. That will shutdown an aftermarket alarm and vehicle should crank

LOOK FOR THE BLACK BOX ALARM AND UNOPLUG THE WIRES ON IT LIKE 12 WIRES OR SO ONE PLUG

do the lights go out when trying the starter? check the battery and connections get the battery tested, see if its good.. repost findings..

It sounds like you probably have a shorted battery cell. This will not only cause the repeated clicking that you described, but it will also rob power when jump-starting from another vehicle. There is probably enough power when jump starting to turn the starter over, but after the starter take the power that it needs, there is not enough power to operate the computer system....so I have no doubt that you probably are not getting any fuel. The computer has to tell the fuel pump to run. If there is no power for the computer....I think you can figure it out from here.

Replace the battery and try it again.

Please also review this article: My Car Won't Turn Over

Your starter may be the problem. Is that why you bought a new battery?

you should check the voltage on your batttery when the car is running. If it reads about 13.5 to 14 volts, your alternator is doing it's job. If it's less, replace the alternator. If the alternator is ok, you have a power drain somewhere, you will need a proffesional to look at it.

with a new starter, this sounds like a bad battery cable or terminal end. the easier way to figure this out w/out checking the voltage drop across a whole battery cable is to affix the jumper cables strategically to find the bad one. Put jumper (+) on batt (+) and jumper (-) directly onto a piece of unpainted engine metal and not in the way of moving parts. If it starts this way then you've got a bad ground cable. If it didn't start, put jumper (+) on the hot post of the starter solenoid (there are 2 posts, only touch the one w/ the fatter cable going to it) or on a remote jump point if equipped, and put jumper (-) to batt (-). If it now starts you need a positive battery cable, or just a battery-to-starter cable (if separate)

please clarify does it start or not ??

You should have a heavy red wire going to the back of the alternator, it should have 12 volts, it will excite the alternator, thus allowing it to charge your battery. If the doesn't have 12 volt, trace the wire, I believe that it will end at the starter. If you have 12 volts at this wire, most likely you have a fusable link thats shorted out at the starter. Look for a wire at the starter that appears burnt, or wiggle the wires one at a time, you'll find on that feels like a plain rubberband, with no resistance while wiggling.

Hi FrostyRage.
I believe your remote start is jumping where your problem area is. I believe it to be somewhere in the wiring leading away from your ignition switch, best guess that I have.

Greg.