-- Oracle 21c: JSON_MERGEPATCH Function
-- JSON data can be revised as shown below
-- To remove data, the keyword "null" is case sensitive (as shown)

WITH json_data 
AS (
SELECT  '{ "Customer":"ABC Co.", "PONumber":1600}'  po_data 
FROM  DUAL
)
SELECT  po_data JSON_MERGEPATH_PO_Data
FROM  json_data
UNION
SELECT  JSON_MERGEPATCH(po_data, '{"Customer":"DEF Co."}')
FROM DUAL
FROM  json_data
UNION
SELECT  JSON_MERGEPATCH(po_data, '{"PONumber":99999}')
FROM DUAL
FROM  json_data
UNION
SELECT  JSON_MERGEPATCH(po_data, '{"PONumber":null}')  --Case sensitive 
FROM DUAL
FROM  json_data
;