try this, bit long winded but should get the job done. will need amending to handle multiple duplicated records but should get you started,
;with ctedata as (select 1 as idnum, 1 as memberid, 'ABC' as name
union all select 1, 2, 'BCD'
union all select 1, 1, 'ABC'
union all select 1, 3, 'GCD'
union all select 1, 6, 'PLX')
select memberid into #memberDups from #members group by memberid having count(*) > 1;
while exists(select * from #memberDups)
declare @currmem int;
select @currmem = memberid from #memberDups;
with cte_memDs as (select top 1 * from #members where memberid = @currmem)
delete from cte_memDs;
delete from #memberDups where memberid = @currmem;
select * from #members;
drop table #members;
drop table #memberDups;