Termination of Parental Rights

My daughter's father and I were not married, however, he did sign the birth certificate and she has his last name. He has never consistently been in her life. She is six years old and he has been out of her life more than in her life. He is now serving a long prison sentence and has never paid child support. I am financially stable with a career and want to know if my circumstances would allow me to terminate any parental rights he has or could potentially have if he were to get out early. We keep in contact through letters. He is unfit with past drug addictions and a repeat offender. Please let me know my legal options.