Offline backup devices (Deduplication storage folder, B2D, tape drive etc) cannot be deleted in Backup Exec 2012.
“<devicename> is currently in use by a job. Please wait until all jobs have finished before you delete it.”
A hotfix is now available for this issue in the current version(s) of the product(s) mentioned in this article. Refer to the Hotfix link under Related Documents at the end of this article to obtain the hotfix needed to resolve the issue.
Backup Exec 2012 Rev 1798 Service Pack 3 (TECH205351).