Keep the Incident but Remove the Files

I am getting Corrupted incident received Code 1802

I work in a very big enterprise and we are currently on our 10th Database in Oracle at 33gb a piece. Slowly we are running out of space. I've done some reserach but the answers didn't seem to be very clear.

1. What can be done to reuse Tablespace? I've deleted 50k incidents and there wasn't any space free'd up. How do you TRULY purge tablespace. I understand that Oracle won't consolidate the free space but there doesn't seem to be any free space at all after deleting a large amount of incidents.

2. We do image monitoring through e-mail. If the image is harmless, what can I do to keep the incident but get rid of the image itself to help save on space?

Thanks!