keep data for 4 weeks

Gurus

I am very new to BU and I have a legacy BU server here, I was trying to clean tapes for a new jobs on our loader and there are some tapes that came across as "keep data fro 4 weeks" I tried to associate this tapes the the scratch media so I can use them again but "nada" they just keep the retencion period, what  can I do to makesthis tapes scratchables again and be able to use them.

Thanks for any help