Horn just goes on its not the alarm so took horn use out

Ground wire bad on alarm horn under hood. Fuse blown on line to horn under hood. Fuse blown to alarm system. Bad ground on alarm system.

Depending if it is a aftermarket or a factory alarm, they should all have fuses that can be removed. By removing the fuse, you may lose your keyless entry option. Most aftermarket alarms have a siren that is usually mounted under the hood in the engine compartment area. I've seen where people have cut the wire going to the siren to disable it but keep the power going to the alarm system to keep the keyless entry still functional if it came with the alarm system.
Factory alarms usually use the existing horn for the alarm. If that is the case, you might need someone who is experienced to disable the circuit so that the horn will not sound if alarm goes off but the horn will still be functional when needed. Hope this helps.

can be 4 things, as is true with all puters, as that is what it is.
1: bad inputs to the alarm (wires are corroded, shrink cold and fail)
2: bad sensors.
3: bad alarm processor.
4: bad outputs, ( the horn is a shared resource , so can be the horn stuck?)

to find this take real hard work. and tools for monitoring all inputs
to the alarm and see what fails. THE FSM covers all that
read the FSM and ask questions if any.

You have 2 point of contact one is the alarm and the other is the horn switch itself, the horn switch is non op,

take the fuse out for the alarm

If the horn fuse ( Fuse #26 ) is installed and has power on both sides of the fuse, you might want to check that the horn connector is still on the horns.

The horn relay is not serviceable in the fuse panel.

You can test the horn connector for power, the Yellow w/ Light Green wire, when the horn button is pressed.

The usual cause of this is the alarm switch on the bonnet panel is too low and creeps up when you leave the car .

Just put some washers behind it so its snug when the bonnets shut down - I have done a few like his and its easier than disconnecting .

Have you tried resetting the alarm, or even disconnecting the car battery and reconnecting it... also make sure all doors and trunk lid is closed

i took the car to a mechanic and had the alarm system disconnected and the horn reconnected

can't find the horn or the horn wire?... if it's the wire you need to power, it's the black wire at the steering column, I would need make and model of the alarm you have to tell you which wire to connect to activate the horn when the alarm goes of or is armed or disarmed.