Right being a certified toad alarm installer this is a easy one.
Depending on the model of alarm, you may have a separate alarm module or a compact system which has it all built into the power sounder. The way to tell is if it has a plug on the sounder which means its a compact system.
Locate the alarm module (black box with toad written on it).
It will have a large plug with the main wires going into it.
You will need to trace back from this loom and you will see where the fitter has spliced into the loom.
It will be linked to the fuel relay, management relay more than likely.
If they have done a tidy job they will have spliced in in different locations, this is just a case of following the wires back.
Once you have traced it back its a matter of cutting the alarm wires off 1 at a time and re linking the original wires.
The wires will match in colour code so straight forward.
The other plugs into the alarm module will be for the ultrasonic sensors , these just unplug.
The wires going into the engine bay will be for the power sounder, bonnet switch, and possibly the power supply if there is a fused wire.
If you have any questions just PM me.
Gareth