BUT they keep appearing on hubbys iMac (in same room) if he deletes from his it deletes from mine
Are your files all saved to iCloud and do you share the same Apple ID? This might explain why both iMacs are synchronising file saves/deletes.
Also can I disable the dcim thingy
The DCIM folder is used by digital cameras to store the pics they take. Although the folder is required on the memory card used in the camera, you can move the pictures from the card to the iMac without having to use the DCIM folder.