Android Studio 0.8.2: Remove Vertical Line Break

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

In Android Studio 1.1.0:
File > Settings > Editor > Appearance > Show right margin (uncheck)

update:

AS 3.x:

Editor -> General -> Appearance -> Show hard wrap guide

With Android Studio 1.2.2

File > Settings > Editor > General > Appearance

Or you can just write in the search box of Settings: "right margin"

In Android Studio 3.1.2, Show right margin is replaced by Show hard wrap guide. (I don't know in which release, this change rolled-out)