I'm w/o a pituitary gland due to brain tumor removal 15 yrs ago. I am on Orthotricyclen lo to have my period. Do I even need to have a period?

Yes and no. While it's not necessary to specifically have periods, it is important to replace female sex hormones that your body would've naturally produced. Not taking birth control pills would effectively send you into a a very very early menopause which has its own long terms risks in someone as young as you. Good luck!