I have 2 boys and their father doesen't pay child support or see the kids in almost 2 years.I'M thinking of chaning their last name,if I do is he still intitle to pay support even if he sign his rights over which I want him to do also

Until another person adopts these kids, he will be paying child support.

First, you cannot legally change their names without his permission. Second, The likelihood of getting is rights terminated is extremely slim. Generally, a court will only grant a TPR to clear the way for an adoption or if the parent represents a danger to the children.