Drop all tables and sequences in postgres

gistfile1.sql

# tables for owned by 'tableowner'
select 'drop table if exists "' || tablename || '" cascade;' from pg_tables where tableowner='tableowner';
# all sequences
select 'drop sequence if exists "' || relname || '" cascade;' from pg_class where relkind = 'S';

#All tables in current_schema(), replace by your schema name if you're not in current_schema()

DO $$ DECLARE
    r RECORD;
BEGIN
    FOR r IN (SELECT tablename FROM pg_tables WHERE schemaname = current_schema()) LOOP
        EXECUTE 'DROP TABLE IF EXISTS ' || quote_ident(r.tablename) || ' CASCADE';
    END LOOP;
END $$;

#All sequences

DO $$ DECLARE
    r RECORD;
BEGIN
    FOR r IN (SELECT relname FROM pg_class where relkind = 'S') LOOP
        EXECUTE 'DROP SEQUENCE IF EXISTS ' || quote_ident(r.relname) || ' CASCADE';
    END LOOP;
END $$;