Can a Villager vote himself?
No version of werewolf I have found forbids a player from voting for him/herself during the day.



The Werewolves of Miller's Hollow


  The players, after much debating and arguing, must select one player that they want to eliminate when they vote.




Stellar Factory Werewolf (playwerewolf.co)


  Daytime is very simple; all the living players gather in the village and decide who to kill. As soon as a majority of players vote for a particular player to kill, the moderator says "Ok, you're dead."




Ultimate Werewolf


  Each day, the players discuss who among them is a werewolf, and vote out a player.