How to leave current guild

In order to leave the guild and not to lose 10 aligment - your character must be offline and kicked from the guild by one of leaders.

Open 'Guild management' page either from your browser or from the in-game menu

Just press 'Leave guild' button and confirm your action in a pop-up window

and confirm your action in a pop-up window or press 'No' if you accidentally change your mind :)