Return Alpha values from a ID field

I need to pull out only the alpha characters from an ID file not numeric values, but this returns the numeric values as well

Please assist have found the following for DB2
SELECT CIN, NATIONAL_ID,FNAME,MNAME,LNAME1,LNAME2
FROM    Prodmgr.T_Consumer
WHERE   CIN  NOT IN  (SELECT CIN FROM Prodmgr.T_REPORT_CONSUMER)
and NATIONAL_ID not like '%?%?'
and ( National_ID not in '%A%'or National_ID LIKE '%B%'or National_ID LIKE '%C%'
or National_ID LIKE '%D%'or National_ID LIKE '%E%'or National_ID LIKE '%F%'
or National_ID LIKE '%G%'or National_ID LIKE '%H%'or National_ID LIKE '%I%'
or National_ID LIKE '%J%'or National_ID LIKE '%K%'or National_ID LIKE '%L%'
or National_ID LIKE '%M%'or National_ID LIKE '%N%'or National_ID LIKE '%O%'
or National_ID LIKE '%P%'or National_ID LIKE '%R%'or National_ID LIKE '%S%'
or National_ID LIKE '%T%'or National_ID LIKE '%U%'or National_ID LIKE '%V%'
or National_ID LIKE '%w%'or National_ID LIKE '%X%'or National_ID LIKE '%Y%'
or National_ID LIKE '%Z%')
ORDER by National_ID DESC;