Can you please assist me on how do I create a role with snapshot consolidation permission only?
Did you try creating role with privilege Virtual Machine -> Snapshot management -> remove snapshot Only.
untick remaining three Create, Rename and Revert, that should give you Remove/Consolidate only role.
Second >>> I want to designate another permission to them in which they can only remove the HDD from the VM and DONOT have option to delete it from disk.
The permission available in the roles enables both the options for HDD removal from VM and delete from disk.
For the above, I think there's no such privilege available to control that.
Virtual machine -> configuration -> Remove Disk is the privilege controls both the options together.