title: How do I stop docker's virtual machine so I can install VirtualBox?
body: <p>I am on a Mac. I installed docker and ran the terminal. It starts the virtual machine. Now I want to install VirtualBox but the installation program complains that there is a virtual machine running that I must stop first. I exited the terminal and it said things about saving stuff but the VirtualBox installation program still says I need to stop a virtual machine. How do I do that? Since I don't have Virtualbox installed yet I don't know how to access it... </p>