Been searching through the editor settings for quite a while but I can't figure out how to turn off the vertical line break in Android Studios 0.8.2. Driving me crazy!!!
It was driving me crazy as well. For older versions (like 0.8.2), Open the Options and uncheck:
Editor -> Appearance -> Show right margin
More recent versions use:
Editor -> General -> Appearance -> Show right margin
AS 3.x:
Editor -> General -> Appearance -> Show hard wrap guide