If my sister and I own a house together and have a mortgage loan together as well, can I have my name removed from both?

you could quitclaim deed the property to her to put it in her name.  BUT  you are on the debt for the mortgage and will continue to be on it regardless of whether you own the proiperty.  if she could refinance, then that would take you off.  or sell it .

you can file a suit in court to get an oprder to sell the property if she will not do what you want her to do.