Power off the VM (enter in the guest and make a shutdown, or reboot your ESX, or use ps and kill from your ESX console).
Then create a new VM with the same hardware configuration of the original one.
Finally from the ESX service console, use cp (or mv) command to overwrite the new (emply) flat file, with the old one.
Andre
Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro