Role vote is for removing people from their class and only applies to classes that are the basic rifleman (no point kicking someone from an unlimited role). Squad Leader isn't a class in RS2, so you can't vote them out of it. If you're unhappy with your squad leader, you should either ask them to promote you to the position, or leave and start your own squad (and send squad invites to your former squad mates in the hope that they'll join you). You can't vote to kick someone out of a squad that they started though.