Try the following queries. It will give you two .sql files (create_fkeys.sql & drop_fkeys.sql).
First review them to make sure they look ok.
Then execute the drop_fkeys.sql
ie: \i drop_fkeys.sql
Do your deletes, then rebuild your fk's with
\i create_fkeys.sql
Good luck.
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-- CREATE STATEMENT FOR ALL FK's
\o create_fkeys.sql
SELECT E'\\timing';
SELECT 'ALTER TABLE ' || n.nspname || '.' || '"' || t.relname || '"'
|| ' ADD CONSTRAINT ' || '"' || c.conname || '"'
|| ' '
|| pg_get_constraintdef( c.oid)
|| ';'
FROM pg_class t
JOIN pg_constraint c ON ( c.conrelid = t.OID AND c.contype = 'f')
JOIN pg_namespace n ON (n.oid = t.relnamespace)
JOIN pg_class f ON (f.oid = c.confrelid)
WHERE c.contype = 'f'
AND t.relkind = 'r'
AND t.relname NOT LIKE 'pg_%'
AND t.relname NOT LIKE 'sql_%'
ORDER BY n.nspname,
t.relname;
-- DROP FK's
\o drop_fkeys.sql
SELECT E'\\timing';
SELECT 'ALTER TABLE ' || n.nspname || '.' || '"' || t.relname || '"'
|| ' DROP CONSTRAINT ' || '"' || c.conname || '"' || ' CASCADE;'
FROM pg_class t
JOIN pg_constraint c ON ( c.conrelid = t.OID AND c.contype = 'f')
JOIN pg_namespace n ON (n.oid = t.relnamespace)
JOIN pg_class f ON (f.oid = c.confrelid)
WHERE c.contype = 'f'
AND t.relkind = 'r'
AND t.relname NOT LIKE 'pg_%'
AND t.relname NOT LIKE 'sql_%'
ORDER BY 1;