You haven't provided enough facts here to really give you good information.
First, you can't sign over parental rights like a car title. Termination of parental rights is something that the court must do. You do have the option of filing a petition for voluntary termination of parental rights; you would do so in Milwaukee County court.
Once your parental rights have been terminated, ordinarily you have no rights or duties with respect to that child. Every case is different and this will be a fact-intensive inquiry with the court. In general, public policy does not favor leaving children without means of support.
I will give you some solid advice: get an attorney. Termination of parental rights is serious stuff and you need to make sure that you understand all of your rights and duties.
