Virtual machines or guest OS could take you too much storage space on the host machine. If you no longer use or need a virtual machine, you may consider removing virtual machines from your computer to free up disk space. If you use Oracle VM VirtualBox for Mac, you can delete virtual machines from VirtualBox following these steps.
Launch VirtualBox from the Launchpad or find it from Spotlight Search and quickly open it from there. The VM VirtualBox Manager screen opens. On the left sidebar, you will see the list of all virtual machines or guest OS. Select the virtual machine and OS you want to delete.
Right-click on the virtual machine name, or press and hold the Control key when you click on the guest OS, then choose Remove from the context menu. Alternatively, go to Machine from the top menu bar and choose Remove.
You will see a warning message with options to only remove it from Oracle VM VirtualBox Manager or completely delete the guest operating system and all associated files from VirtualBox. If you want to free up storage space, choose Delete all files.