Advice full custody

I need advice. I have a friend and she has been in a terrible relationship with this man. He would constantly hit her and cheat on her even with her sister. They have a two year old together and he fought to be in her life. He asked for a DNA test a year ago and since it came back positive he has visiting rights and has to pay child support which he hasn’t been paying. My friend wants to get full custody because every time her baby goes with him she gets home like she has been crying all day and it breaks her heart. She just doesn’t want him to be around. What can she do? Any advice? He even report the baby in his taxes without her consent and kept the stimulus check even if he doesn’t provide for her.