Should I shave or clip my hair before surgery for the removal of 2cm bcc on the crown of my scalp?

No. As surgeons, we can work around hair accordingly, if needed. Sometimes the hair will be cut around the area of the tumor, if need be. Also too, shaving can potentially increase the risk of wound infection, if done within 24 hours of a surgery, as this can lift superficial skin cells and disrupt the environment near the tumor.

No, you don't need to do anything like shave or clip your hair unless you doctor specifically asked you to. Most of the time I will use clips if needed, or frankly, the assistant is there to help with holding the hair in place. There's no need for you to be concerned and try to prep. "This answer has been solicited without seeing this patient and cannot
be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."