Re: (un)grouping question

Don't this satisfy your requirement?
(This isn't tested. There may be some syntax error.)
DELETE FROM your_table T
 WHERE uid >
       (SELECT MIN(uid)
          FROM your_table M
         WHERE M.somevalue = T.somevalue
       )
;

The result I expected is:
SELECT * FROM your_table;

uid|somevalue
--------------------
1|11
3|31
6|33
2|44
5|71