SQL Select everything after character

Using string split available from SQLServer 2016

;with cte
as
(
 select 
*,row_number() over (order by (select null)) as rownum
 from string_split('abcd-efgh-XXXX','-')
)
select top 1 * from cte 
order by rownum desc

DECLARE @x varchar(100)
SET @x = 'abcd-efgh-XXXX'
SELECT RIGHT(@x, CHARINDEX('-', REVERSE(@x)) - 1)

You can use:

select right(col, charindex('-', reverse(col)) - 1)