If the biological farther signs his rights away to avoid paying child support - does he has to go to court for this and will this be legal and will he no longer have to pay child support?

If you had read any of the millions of questions posted here already dealing with this question, you'd know that you can give up your rights, but NOT your obligations.

Giving up your rights means you have no say in how the child support money you will still have to pay will be spent.

Signing away rights has nothing to do with stoping child support unless the child is being adopted by a step partner or step parent.

And yes it will all need to go though the courts.