method to merge differential VHD

[takeru]

I run a VM with a VHD formatted virtual HDD.
Once I created another temporary VM with the same VHD for testing, so that the system created two differential VHD trees.
Now I have dropped the temporary VM, but the VHD remains a static parents with differential VHD which costs me so much storage overhead.
I cannot see any snapshots on the VirtualBox console, and cannot find any user interface to merge the differential VHDs.

Is there any method to manage such a situation?

[MarkCranness]

Instructions here should let you clonehd/merge the differencing disks:
http://forum.virtualbox.org/viewtopic.p ... 06#p106206
Ignore the parts about finding which differencing disks are attached to which snapshot (you have no snapshots), use VHD in place of VDI, and just directly clonehd the {hexUUID}.vhd file using the hexUUID, for example:
VBoxManage clonehd b6441469-5ccb-418c-8fdd-73c5e1a17314 CloneDisk.vhd --format VHD