Every showerhead is different with regards to what type of water restrictor is in them. Most just pull out of the handle where the hose connects. Some will not come out. I am a plumber and I remove them all of the time. If I can't pull it out with a dental pick or needle nose pliers, I screw a small wood screw into it and pull it out with Channellocks. If the restrictor is not removable, sometimes there is a small o-ring that can be removed and that is good enough. Very rarely do I have to drill a hole through a restrictor, but if I do, I just have at it with a drill bit somewhere around 3/8". I make sure I get any drill shavings out before I reconnect the hose as they may be impossible to get out later.
2016 Rockwood Windjammer 3029W Diamond
2015 Chevy 3500HD LTZ 6.0 Crew Cab 4x4 Long Bed 4.10:1 SRW