Return the bolt. You need to turn it out only for a half inch, then easily strike it with a hammer. (Don't make a strong strike, to not drive in the quill stem if it rusted!) Usually it will be enough, Yet it can be a little rusted, so hitting with your hand on the handles will help. Sometimes it's very rusted, so you will need to use some oil to deal with it. Very rarely it rusted so much, that nothing will help.