If follicular epithelial cells are present is surgery to remove the thyroid necessary?

No: If the cells are from a fine needle aspiration they could be normal. You need to see a thyroidologist.

Follicular lesion: I assume you had a needle biopsy that identified follicular cells and your doctor is recommending removal of that lobe. A needle biopsy is not able to differentiate between a benign or malignant follicular tumor so surgery is the usual recommendation to clarify that situation.