You should be able to pull the fuse for the door locks; the mechanical lock buttons and key will continue to work. To find out which fuse, just Google "[car make] [model] [year] fuse diagram" and look for door lock actuators or similar.
Also, most (if not all) car user manuals come with a diagram of the fuse box.
Some even have a diagram of the fuse box in the fuse box.
Guess and check is also a reasonable solution. Last time I had a fuse go, we just moved them around until all the essentials were working.
Yes, you don't mount the mechanism that opens the doors when installing the alarm (or cut the wires afterwards).
Store bought alarms have a lot of crap the electrician never hooks up so what's the difference not mounting this one.