Manually deleting images, catalog has no record of

I have about 4.5 TB on a basic disk storage unit that isnt valid I just discovered. The partition is 7TB used for Server_Diff storage.  This storage unit is for Diffs only and actively being written too without issue.  I notice these images are not listed in the catalog for the clients.  I did a search and didnt see anything identical to this issue in the forms.  If I delete these images manually is this going to cause any issues.  My thought is no based on my understanding, but I would love a more knowledgeable confirmation.  Thanks.

EDIT:  The images here shouldnt be older than 2 weeks based on retention.  Some are 2-3 months old.