Resizing virtual box storage

Microsoft Windows [Version 10.0.10240]
(c) 2015 Microsoft Corporation. All rights reserved.

C:\Users\user>cd C:\Program Files\Oracle\VirtualBox

C:\Program Files\Oracle\VirtualBox>vboxmanage modifyhd "C:\Users\user\VirtualBox VMs\Design\Design.vdi" --resize 81920
0%...
Progress state: VBOX_E_NOT_SUPPORTED
VBoxManage.exe: error: Resize hard disk operation for this format is not implemented yet!

C:\Program Files\Oracle\VirtualBox>vboxmanage clonehd "C:\Users\user\VirtualBox VMs\Design\Design.vdi" "C:\users\user\virtualbox vms\design\design_cl.vdi" --format vdi
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Clone hard disk created in format 'vdi'. UUID: e883d1c3-02a1-43da-97c4-522c1b4be8eb

C:\Program Files\Oracle\VirtualBox>vboxmanage modifyhd "C:\Users\user\VirtualBox VMs\Design\Design_cl.vdi" --resize 81920
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

C:\Program Files\Oracle\VirtualBox>