I'm not an expert

but have U tryed using the retention period?

You have not said which version of Backup Exec and whether the jobs are standard backup to disk (using BKF files) or GRT based (using IMG folders) kind of makes a difference as to how to solve your issue.

The basic answer is makes sure your overwrite protection settings do allow media to be overwritten and that overwrite jobs do periodically run - however if GRT is being used then the version of Backup Exec makes a huge difference as to how the deletion of recyclable IMG folders works.

Cant seem to find the retention period option

Hi its version 12.5

Its using normal backup to disk option.  If there is a better one then im all ears!!

OK with normal backup to disk - so not backing up Exchange, AD, Sharepoint etc with the granular options (GRT) then the overwrite of the Media (BKF) files are controlled by

1) The Media Set Overwrite Protection Period (for the media sets specified in the jobs)
2) Whether the jobs starts as an Append or an overwrite (and if an append whether appendeable media are available or not)
3) The Append period
4) Whether the system is set to use recyclable media before scratch or scratch before recyclable (this might not affact BKF files too much though as has a greater affect on tapes)

Bear in mind that the overwrite period starts at the end of the last job to use the media so:
a) if you job takes 6 hours to run and you want to overwrite the media every week then it will not be overwriteable at the start of the next running of the job if you set an overwrite protection period of 1 week (6.5 days configured in hours would allow it)
b) if you append to the media with a second job then the overwriteable date moves back again to be based on the end of the append job - which requires a further reduction in yoru overwrite period.