I no long need child support from the noncustodial parent how do I stop it in Arkansas

You can obtain a court order to that effect.
It sounds stupid, but you can ask for what you want.

Child support isn't about what you want or need. It's about parent's fulfilling their obligations to their children. You can go to court and petition to modify the support order but I have to ask, why would you stop your children from receiving financial support from the other parent?