SQL Server 2012

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

create table tbl (t1 int, t2 varchar(10), t3 varchar(10));
insert into tbl (t1, t2, t3) values
(1,     '01',    'M6'),
(1,     '02',    'M6'),
(2,     '01',    'M1'),
(2,     '01',    'M1'),
(2,     '02',    'M1'),
(3,     '04',    'M4'),
(3,     '04',    'M4'),
(4,     '01',    'M1'),
(4,     '01',    'M2');
9 rows affected

with cte as (
  select 
    t1, t2, t3, 
    ROW_NUMBER() OVER (PARTITION BY t1, t2, t3 order by t1, t2, t3) rn from tbl
)
delete from cte
where rn > 1;
2 rows affected

select * from tbl


t1
t2
t3


1
01
M6

1
02
M6

2
01
M1

2
02
M1

3
04
M4

4
01
M1

4
01
M2