Do you HAVE to neuter him? No. But it is better for him, and will be better for you, too. How old is he right now? He will begin to spray at about 4-5 months, depending on his breed. (Smaller breeds mature faster.) He may also hump you, stuffed animals, the cat, anything that he can get ahold of. A neutered buck is almost always calmer, friendlier and more cuddly than an intact male.
Sadly, a lot of people have "never heard of" neutering/spaying rabbits. It is, however, just as recomended for a rabbit as for a cat or a dog. Plus the fact that rabbits can reproduce much faster and at higher rates than cats or dogs. I don't know if you have any other rabbits, but I will throw this in just as an interesting rabbit fact. A doe rabbit in constant contact with a buck can, and will, have a litter every four weeks. Rabbits do not go into heat, they can get pregnant at any time. And it only takes about ten seconds to happen! Congratulations on getting your little guy, and welcome to RO. :biggrin2: