Docker reset on Linux

I have been advised by a Mac user to do a reset from the preferences window using the bomb icon. However, I don’t have a Mac; I have Ubuntu 16.04. I don’t find any Docker Gui at all–though it’s possible I’m looking in the wrong place. Is there a cil command that will do the same thing? Thank you. PS. My docker is 18.03.1-ce, build 9ee9f40 .

Thank you for your help. I got what I wanted by purging docker and deleting /etc/docker and /var/lib/docker .

I was using Lando over top Docker. Lando beta (they have no goldens yet) 39 works for me but 42 didn’t. Since I’m not accessing Docker directly but rather through Lando, I don’t know whether the root user thing was the issue.