Deleting old backup files

Hi, 

I'm very new to backup exec (2012). In my environment, files are saved to the appliance on D:\BEData (this seems to be the norm for most users). 

I need to be able to delete backups for jobs that no longer exist, and am unable to decipher which files/folder belong to those old jobs. 

What I see are a lot of folders that are labled "IMG00####" (where # is a random number). 

Any help on the matter would be greatly appreciated. 

Thanks.