Freelander 2 (LR2) Siren Alarm

Hi
My Freelander 2 2008 manual was making a loud ticking noise yesterday, engine off or on
Traced it to the siren alarm mounted on bulkhead beside battery
Removed plug and the unit
Unit still ticking loudly
Tested car alarm and it still works as normal with the unit off, flashing and sound
So to the question!
Do I need to replace the unit, £25.00 ebay, £60.00 dealer
Or can I just leave it off and forget about it
Many thanks in advance

If you leave it off don’t forget to tell your insurance.

Would carry on ticking as it has a battery backup in it.

I would replace with a genuine brand new one for the money.