sole legal/physical custody of my kids wnat ot go to mexico to live for a year do i need fathers permission or need to go to court ?

Short answer (presuming you are talking about a relocation, not just a vacation): yes.  Under Nevada law, "If custody has been established and the custodial parent intends to move his or her residence to a place outside of this State and to take the child with him or her, the custodial parent must, as soon as possible and before the planned move, attempt to obtain the written consent of the noncustodial parent to move the child from this State. If the noncustodial parent refuses to give that consent, the custodial parent shall, before leaving this State with the child, petition the court for permission to move the child. The failure of a parent to comply with the provisions of this section may be considered as a factor if a change of custody is requested by the noncustodial parent."