People often ask if they should be trimming parts off of their Venus Flytrap, and the answer to this is yes, if it is black. It isn’t necessary to trim or remove the black pieces that are left when traps die (a natural process, traps die off after eating a certain number of times, usually 4-5, and after time, and always new growth should also be coming in, even during dormancy). However, it does look nicer and neater to trim them, and too much dead debris could potentially keep the sun’s UV rays from touching the plant. This is why you would especially want to remove dead matter after dormancy has ended, because it can build up too much and keep the plant from all the UV it could be getting.
You don’t want to remove any green matter, as it is still helping feed your Flytrap, using chlorophyll. And please goodness do not trim any root or rhizome material (someone actually did this, cut the roots off like a haircut, oh my goodness, it hurt me inside).
Usually you don’t even need scissors, the dead material will dry up and become crunchy and come off easily using your fingers.
One little note, be careful to try and not trip any traps if you are manicuring your Flytrap. It takes a ton of energy to close a trap, so you only want to do that if you have food to offer.