I have just tried that but got this message:
This tool does not check for the existence of Virtual Machine snapshots or linked clones.
The use of this tool on a vmdk file that has a snapshot or linked clone associated with it
can result in unrecoverable data loss and/or data corruption.
Are you sure that no snapshots/linked clones exist for this vmdk? (y/n)
Obviously I could say yes and it would carry on, but I don't think that's sensible. Is this behaviour that you would expect?