To remove the specified Characters in the Given String

Alphabetic only: SELECT dbo.fn_StripCharacters('a1!s2@d3#f4$', '^a-z')
Numeric only: SELECT dbo.fn_StripCharacters('a1!s2@d3#f4$', '^0-9+-/')
Alphanumeric only: SELECT dbo.fn_StripCharacters('a1!s2@d3#f4$', '^a-z0-9')
Non-alphanumeric: SELECT dbo.fn_StripCharacters('a1!s2@d3#f4$', 'a-z0-9')

CREATE FUNCTION GEN_FN_StripCharacters

(

    @strInputString NVARCHAR(MAX), 

    @strMatchExpression VARCHAR(255)

)

/*

---Created By : Ram    

--Date : 15-Feb-2013

--- Purpose : To remove the specified Characters in the Given String

Alphabetic only: SELECT dbo.fn_StripCharacters('a1!s2@d3#f4$', '^a-z')

Numeric only: SELECT dbo.fn_StripCharacters('a1!s2@d3#f4$', '^0-9+-/')

Alphanumeric only: SELECT dbo.fn_StripCharacters('a1!s2@d3#f4$', '^a-z0-9')

Non-alphanumeric: SELECT dbo.fn_StripCharacters('a1!s2@d3#f4$', 'a-z0-9')

*/

RETURNS NVARCHAR(MAX)

AS

BEGIN

    SET @strMatchExpression =  '%['+@strMatchExpression+']%'

    WHILE PatIndex(@strMatchExpression, @strInputString) > 0

        SET @strInputString = Stuff(@strInputString, PatIndex(@strMatchExpression, @strInputString), 1, '')

    RETURN @strInputString

END

http://www.sqlservercentral.com/scripts/Remove+character+or+number+from+String/99755/