sometimes you can sex them while they are crawling up the wall of the aquarium, but rarely. its still hard lol.
if it is a boy, then its penis will be on the same side that the spiral is on, and it is not speckley like the air syphon. it will be solid white. the air syphon is on the opposite side of the spiral.
but, like tori said, it is very simple to get rid of clutches. they lay them above the water line, sometimes on the lid of the aquarium, and you can remove them then and freeze them and flush or throw away. be sure to wait at least 24 hours after it has been laid though, or it will squash all over and be messy and slimy.