How to delete database from the inside, with only access to that database.
The primary way this works is by using
pg_dump's ability to drop a schema before recreating it.
This creates a dump of the database without any data, and with a fresh schema (drop then rebuild). This output is then
grep'd to only contain the drops.
pg_dump -cs "postgres://<database url>" | grep DROP > drops.psql.sql
Now run the drops. These drops are specifically designed for this schema so should be complete and in the correct order.
psql "postgres://<database url>" < drops.psql.sql