Remove unused Layouts in Oracle Apex

 Tables used :

APEX_XXXXXXX.WWV_FLOW_REPORT_LAYOUTS 

APEX_XXXXXXX.WWV_FLOW_SHARED_QUERIES




use the following query to delete unused Layouts.

make sure you do have backup before .




DELETE FROM APEX_220100.WWV_FLOW_REPORT_LAYOUTS ll

      WHERE NOT EXISTS

                (SELECT 1

                   FROM APEX_220100.WWV_FLOW_SHARED_QUERIES qq

                  WHERE qq.REPORT_LAYOUT_ID = ll.id);

Thanks : https://stackoverflow.com/questions/21549667/where-are-the-report-queries-and-layouts-stored-in-oracle-apex-3-2