USE AT YOUR OWN RISK!! There., I said it .
The best way to clean up the writable is to let the user log out and attach the writable to a machines that does not have an Appvolumes installed.
This way you can check what information is stored in there and the user could remove files himself afterwards.
i get an error when trying to attach the writable to a systems that does not have app volumes installed on it
That error has got nothing to do with not having appvolumes installed. The thing is that Appvolumes creates a setting in the writable to make sure it won't be deleted by accident.
Just browse to your writable datastore and change the following setting in the .vmdk file (so not the flat file which is the 10GB file or the metadata file which holds appvolumes info).
There should be a setting that is called ddb.deletavble=false, you should change it to ddb.deletable=true. Or just attach the the disk non persistent (so read only) that will do the trick as well.