Car wont start, security system is stopping it i think....

tear it out they arnt worth crap mine on my 87 lx was junk i tore it out. if you dont want to tear it out disconnect it. you may have a weak old battery?

Get rid of the alarm! I had a viper on my car when I first got it, and it ended up messing up the ignition. The alarm wouldn't fully disarm and had a ignition kill. After getting rid of the alarm I ended up replacing the ignition module and starter. My advice is to put in a kill switch or get the lock that goes over the brake or clutch.

i would first try what you did before to get it to work. i think you did and it did not work.

then put it in neutral and be safe and all. then find the starter solenoid. it is on the driver fender. turn the key to run. take the little slide on connector off and touch it to the connection on the solenoid that has a lot of wires and cables attached to it.
the car should start.

next test: put a test light on the slide on wire (not where it slides onto the solenoid). ground the other lead of the test light. try to start the car with the key (pushing the clutch pedal in/having the slushbox in park, etc). does the test light light up?
if not, the clutch safety switch or the alarm starter kill are the most likely culprits.
if you want to retain other alarm features, but get rid of starter kill till you figure out what is wrong:
find all of the alarm wires. look for some relays. there should only be one that has a diode running across the socket (the connector that plugs into a relay). use a test light to confirm that when you turn the key to start, the test light lights up (it should be either terminal 30 or 87A). it normally is terminal 30 that will light up, but some installers dont care, and it does not matter.

if no light, you can use a DMM (not A TEST LIGHT) to check for a ground (it is only .5 amps and a test light will fry it) at terminal 85 or 86 (again, should be 85 but some installers dont follow the rules on what coil terminal is what, since it does not affect the operation of the relay). if you find ground at either (only one will be ground), then the alarm is killing your starting ability.
if you want to disable the starter kill, there are several ways to do it. the easiest is to remove the relay and connect 30 and 87A together. or you could find where they cut the original starter wire and solder it back together.

if you want to ditch the whole alarm, find its main power source and disconnect it. if there is not a battery back up, which it does not sound as though there is, then the alarm should be dead.

i would say try this or anything else that others suggest, and let us know what you find and we can go from there. i kinda tossed out a lot, so you could choose what area you think is at fault.
good luck.

one thing to try is down behind the kick panel area by your left foot. there is a two wired connector that is used to bypass the start on most alarms. Stock there should be a jumper, when installing an alarm remove that and run the alarm wires to both sides. Seeing if a jumper will work is not as time consuming as removing an alarm.