I wanted to try vi mode in bash but now I would like to change it back to normal.
How can I unset -o vi ?
The only two line editing interfaces currently available in bash are vi mode and emacs mode, so all you need to do is set emacs mode again.
set -o emacs
That depends on what you define "normal". If that's turning off line editing, the documented way to unset -o vi is to set +o vi
$ set -o vi
$ set -o|egrep -w "(vi|emacs)"
emacs off
vi on
$ set +o vi
$ set -o|egrep -w "(vi|emacs)"
emacs off
vi off
Chris has already answered if your normal mode is emacs.