There is another similar post here for the same problem.
In that post they mention the bcdedit
command to disable Hyper-V
To disable Hyper-V in order to use VirtualBox, open a command prompt as administrator and run the command:
bcdedit /set hypervisorlaunchtype off
You’ll need to reboot, but then you’ll be all set to run VirtualBox. To turn Hyper-V back on, run:
bcdedit /set hypervisorlaunchtype auto
and then reboot.