[Box Backup] Unclogging data store

[Waldemar Augustyn]

This must have happened millions of time.  My data store became full 
very quickly because I forgot to exclude media files from backup such as 
mpeg, avi, etc.  I thought that was no problem.  I just added the 
exlcusion and SIGHUP'ed the client.  Unfortunately, the data store seems 
to think these files are supposed to remain there and does not delete 
them. 

How do I purge them short of actually deleting them on my computers and 
waiting for data store to sync up?  Thanks.