How to clean a U4/U5

I was fired ( after quitting verbally to my boss who was a friend) from a previous job. They updated my U4/U5 to show that I didn’t follow internal guidelines. This was just because of a jealous boss/ friend because I got a higher paying job elsewhere. So in short is there anyway I can get this completely removed from my U4/U5. I was turned down from another job because of this I don’t mind hiring a lawyer but don’t want to spend the money if there is no possible way. Thank you all for your help