Switching between Docker and VirtualBox on Windows 10
As outlined here, Docker for Windows requires Hyper-V. This needs to be disabled before you can run VirtualBox.
And to start using Docker for Windows again, re-enable Hyper-V:
A reboot is required in both cases.
Note: if you only see 32-bit options when creating a VM in VirtualBox, it could be because you havent disabled Hyper-V. More info here on this issue.