Some municipalities outright ban pizza box recycling. If yours doesn’t, curbside recycling may be OK if:
The bottom of the box is lightly stained.
There are no food remnants, however tiny.
There are no stickers, coupons, and the like affixed to the box.
Pizza box top lids usually remain unspoiled, so you should be able to tear them off for recycling. If there is any doubt about the bottom, put it in the trash to avoid the possibility of costly contamination. Check whether your locality allows pizza boxes in yard waste bins for composting.