You can use REPLACE() to clean it up.
If you only want to display it differently you can do something like:
SELECT REPLACE(REPLACE(field1, '12).', ''), '(12.', '')
FROM table1
ORDER BY REPLACE(REPLACE(field1, '12).', ''), '(12.', '')
You can update it the same way
UPDATE table1 SET field1 = REPLACE(REPLACE(field1, '12).', ''), '(12.', '')