Huge tables, trying to delete OID's taking 6+hours per table

The db is only 2TB, these tables are about 50% of the DB.

Just wondering what I can boost to give me some elevated temp performance for what I would think would be a fairly quick operation.

Give this query more work_mem? Mine are set pretty low, based on previous performance notes, this is a 9.5 server.

Thanks

Tory