Removing Characters and special characters from string in oracle using REGEXP_REPLACE

SELECT  REGEXP_REPLACE('%%213213k$$)($!@#jkj23213bjk123',
'([[:punct:]^[:alpha:]])',
'') RESULT
FROM dual

***************************
Removing charecters

SELECT  REGEXP_REPLACE('%%213213k$$)($!@#jkj23213bjk123',
'([[:alpha:]])',
'') RESULT
FROM dual

************************

Removing Special Characters


SELECT  REGEXP_REPLACE('%%213213k$$)($!@#jkj23213bjk123',
'([[:punct:]])',
'') RESULT
FROM dual