By default, when you delete an attachment through the MRM/RGF UI, the attachment isn’t physically deleted from the SAS Content Server. The attachment is only marked as deleted. However, in an RGF 7.4 hot fix, RGF added the ability to specify that attachments should be physically deleted. See https://support.sas.com/kb/67/467.html.
Note that you should never manually delete objects from the RGF database, e.g. attachment_l table, unless instructed to do so by SAS Technical Support. Also, if you removed an object from the attachment_l table but not from the attachment (history) table, you've caused a database integrity issue. The live tables ( end in _l) should be kept in sync with the history tables (not ending in _l).