To delete a virtual machine, follow these steps:
The virtual machine will then be moved to your organisations Deleted items, akin to the trash on your PC. This provides you or another user within your organisation the chance to reverse the action. Items will remain in the trash for a period of 48 hours.
The deleted items facility primarily exists as a method for you to restore a given machine or similar object, i.e. a disk, to the state it was at the point of deletion. Where a virtual machine is concerned this means that all associated system disks and ISOs will also be restored should you elect to restore the virtual machine. Therefore should you attempt to delete an ISO from your organisation where that ISO is connected with a machine currently in the deleted items, the ISO deletion will fail. This is by design and ensures virtual machine restoration can be restored with all resources they had prior to deletion. To override this you must first manually purge the deleted items.