Time capsule: Error deleting partial image

Time capsule: Error deleting partial image

I have two machines backing up to a Time Capsule. On the disk there a
faulty disk image which was marked as purgeable but cannot be deleted:
2013-08-15 6:00:16.847 PM com.apple.backupd[13566]: Found 1 partially
deleted backup image.
2013-08-15 6:00:26.918 PM com.apple.backupd[13566]: Failed to remove
file://localhost/Volumes/Data/NAME .purgeable/, error: Error
Domain=NSCocoaErrorDomain Code=512 ""NAME .purgeable" couldn't be
removed." UserInfo=0x7f8292c029d0 {NSFilePath=/Volumes/Data/NAME
.purgeable, NSUserStringVariant=(
Remove ), NSUnderlyingError=0x7f8292c02920 "The operation couldn't be
completed. Invalid argument"}
2013-08-15 6:00:26.927 PM com.apple.backupd[13566]: Error deleting partial
image /Volumes/Data/NAME .purgeable: Error Domain=NSCocoaErrorDomain
Code=512 ""NAME .purgeable" couldn't be removed." UserInfo=0x7f8292c029d0
{NSFilePath=/Volumes/Data/NAME .purgeable, NSUserStringVariant=( Remove ),
NSUnderlyingError=0x7f8292c02920 "The operation couldn't be completed.
Invalid argument"}
The image is very small and is not a major problem but I wanted to get rid
of it.
Time Machine is not able to delete it
I tried to mount the drive and
delete it with Finder: the Finder crashes
delete it with rm -rf from the terminal: rm hangs
Any better idea the erase the whole Time Capsule drive? I would rather
keep the file than losing all my old spanshots.