“Is a judge allow to deny paternity test and rule the test out of the court if one is taken?”
Under certain circumstances I could see a judge disallowing admission of a paternity test. If it was administered improperly (chain of control broken) it would be inadmissible. If their is a presumptive father, then the DNA test might not come in on relevancy grounds. If a person had signed a voluntary declaration of paternity, and the time to take it back had passed, a judge also might not want to see such DNA test. There probably are other situations, as well.