Sorry, I meant to reply sooner.
Firstly, I used to be a rope access technician and not an engineer, so take everything I say with a grain of salt
Each cable (or guy-wire) has a pulling force of its own, so with every extra guy-wire destroyed, the remaining ones' impact on the tower will increase. It's a rooftop/skyscraper (?), so there'll probably be a lot of wind (also depends on taller structures in the vicinity).
Your map already has one guy-wire removed, so I'd say that blowing up a second will likely weaken the tower enough to make it collapse. And if not, the shockwave of the bomb explosion will take care of that
Blowing up a cable might seem pretty excessive, but I can't think of another easy and fast way to remove a guy-wire. I wouldn't want to be anywhere near one if it gets cut for example, as the tension of the cable would snap anything and everyone in half in its proximity.
A server/communication booth (aka a "shelter") could be possible, although their placement should be as convenient as possible for cables to go from shelter to tower. For every mobile network operator, there would be a seperate shelter, so you could have a different one for each bombsite.
Power supply is typically just a (set of) cable(s) coming from ground level, so not interesting for a bomb site.
Feel free to reach out if you want more info/references/whatever. Sorry again for the delay.