declare @value varchar(50)
declare @i int

set @value = '123-bb-99'

select @i = patindex('%[^a-zA-Z0-9 ]%', @value)
while @i > 0
begin
 select @value = replace(@value, substring(@value, @i, 1), '')
 select @i = patindex('%[^a-zA-Z0-9 ]%', @value)
end

select @value

--- returns = 123bb99