(a) When a support arrearage is paid in full, the Paternity and Child Support Division shall notify the obligor's employer. The employer then shall reduce the amount of income withheld to cover only the current support obligation.
(b) Once income withholding has been instituted it may be terminated only upon a motion by the obligor or the Division of Paternity and Child Support, upon a showing that either the child and the child's custodian has disappeared for such an extended period of time that it is impossible to forward payment or that an obligation to pay support or arrearages no longer exists.