I have a flap of gum above my below wisdom tooth. is it needed to be removed?

Operculum: If you are asymptomatic, you may be able to leave it. More often than not, the tissue needs to be removed or the tooth needs to be extracted.

Yes: Not possible to get under the flap to properly clean. If your Dentist has told you that treatment is necessary, I wouldn't want to second guess his/her knowledgeable recommendation, especially without a clinical examination and x-rays. Know that having a flap of gum tissue, an operculum, still partially covering a wisdom tooth at age 29 is pathological, not physiologic.