How do I take off this shower head?
The shower head side would appear to have wrenching flats so normally one would use an adjustable wrench on that side. Someone has used pliers and badly scored the surface so if you want to discard the head, then just do the same.

On the supply pipe I use pliers over a rag. It appears that Teflon tape was used to seal the threads, but normally sealing these threads is not necessary. There is supposed to be a soft rubber seal inside the shower head fitting which the end of the supply tube presses against. The water is stopped at that point and never reaches the threads.

I tighten just enough to stop it from leaking. There is no point in over tightening because this over compresses the seal. If it would leak, the leak is only when the shower is on and the leaked water goes down the drain (as opposed to a leak inside a wall).