Do have to sill pay child Support when both of my children tun 18 and are graduatedfrom High School?

Under Wisconsin law, if both of your children are adults and have graduated high school, your obligation to pay child support is over. File a motion with the court to terminate the order; if in Milwaukee County, you can do a "walk in" to the family court commissioner's office with a copy of your divorce decree, birth certificates for your children, and high school diplomas, and the court will terminate the order, providing you are also not paying on child support arrears.