even if you could do this (and I dont know of a way) it wouldnt be that good for your body. Once you start a cycle of cleaning out your uterus (period) it probably wouldnt be good for you just to stop having a period cold turkey, if it is even possible. The only way I know to miss a period is to be on birthcontrol pills and do not take the placebos...
if you are worried about having a period for during sex, (this may not be the reason at all..) there is this new things at walmart (I think they have it there) that is somewhat like a litte cup that you insert in your vagina that covers your cervix. It is used for sex when you are on your period...
anyways..dont know if that helped.