remove all snapshots

hello,

i am running out of space in my Mac computer.

to free some space, i decided to remove the four snapshots that i have of my WinXP virtual machine inside Parallels.

however, Parallels only allows me to delete a snapshot at a time.
or is there a way to remove all the snapshots at once?

anyway, when i tell to remove one of the snapshots, Parallels says that it does not have enough space to make this operation.

how can I delete all snapshots, so that i have more free space in my computer?

Many thanks,
David