How to remove last character in the string , 3 smart ways to handle it

1)

 declare @string varchar(100)='ab,cd,ef,'

 set  @string=  reverse (stuff(reverse(@string), 1, 1, ''))

 print @string

2) declare @string varchar(100)='ab,cd,ef,'

   set @string=  SUBSTRING(@string,1,LEN(ISNULL(@string,''))-1);

   print @string

                       

3) declare @string varchar(100)='ab,cd,ef,'

    set @VARDAYTAS= LEFT(@VARDAYTAS,nullif(LEN(@VARDAYTAS)-1,-1))

    print @string

o/p

ab,cd,ef