1) Select the Storage Tab in the BE2012 Interface.
2) Select your disk storage device and click the ====> for the DETAILS view.
3) In the details view select the Backup Sets option.
4) I just scrolled to the bottom of the list which is the oldest backup sets,
5) Select large groups of backup sets using Shift+Left Click
6) Right click the selected backup sets and select DELETE.
7) Yes to All when prompted to delete.