A Dungeons and Dragons experience using tabletop-like game mechanics can differ wildly depending on the Dungeon Master and how heavily they enforce RAW (Rules As Written). Some Dungeon Masters will not let their players change their characters as they feel it breaks the immersion of the game. Others will let you change elements of your character between sessions if you are not enjoying them anymore, or even let you have your current character leave the party by some means, so you can have a new character come into play.