scroll-bar-mode

scroll-bar-mode is a variable defined in `scroll-bar.el'.
Its value is

right

Documentation:
Specify whether to have vertical scroll bars, and on which side.
Possible values are nil (no scroll bars), `left' (scroll bars on left)
and `right' (scroll bars on right).
To set this variable in a Lisp program, use `set-scroll-bar-mode'
to make it take real effect.
Setting the variable with a customization buffer also takes effect.

You can customize this variable.