One option is to truncate the nodestore_node table. Enter the DB:
psql -U postgres
Check the table size
postgres=# SELECT oid::regclass, reltoastrelid::regclass, pg_relation_size(reltoastrelid) AS toast_size FROM pg_class WHERE relkind = 'r' AND reltoastrelid <> 0 ORDER BY 3 DESC;
Run truncate:
postgres=# TRUNCATE nodestore_node ;