I know this question has been asked before and I have yet to find an answer. Is there a way to completely reset wifi or networking settings of ubuntu 14.04 LTS? I want to reset them, not fix an issue I have.
To delete all connections avaliable to NetworkManager:
echo $( nmcli -t -f UUID con list ) | xargs -n 1 nmcli con delete uuid
(this lists all UUIDs of connections and one by one removes deletes each connection, similar in effect to Marcin's answer , only no need for sudo access)
To reinstall NetworkManager
sudo apt-get --reinstall install NetworkManager