Thanks to everyone for your help! Battery had died by this morning, left the bike wrapped in pillows and duvet last night, just in case :-)
Ended up carving out a small piece of the undertray to remove the alarm unit. Soldered up the loom connections and wrapped in lecky tape, job done! Track bike well on the way to being ready :-)
I reckon if I knew what I was doing the alarm could have been stripped out in under 10 minutes. Which makes it a waste of space!

Anyone want to come round for a hammer party?