how can i delete duplicated records having the same email address ?

I tried to delete the duplicated files using the below query but it throws an error code.

Error code "Explain plan cannot be retrieved - Internal error occurred while processing the query, please contact support team."

LOOP

DELETE FROM "DEVELOPMENT_LIST"

WHERE ROWID IN (SELECT MIN (ROWID)

FROM "DEVELOPMENT_LIST"

GROUP BY EMAIL_ADDRESS_

HAVING COUNT (*) > 1);

EXIT WHEN SQL%NOTFOUND;

END LOOP;

COMMIT;

END;