you are over 21 and really have the right to make that decision. if you are absolutely sure you will never want children. in any event (tragic loss of a child new marriage etc. ) then you just need to make the case with the person (urologist or primary care clinician) who will be doing the vasectomy. make this decision carefully since you have the capability of father a child for decades to come.
i am 23 and have 3 kids can i get a vasectomy?