how to delete duplicate rows in oracle

create table testdup
(
id number(10) not null,
name varchar2(150) not null,
dept number(10) not null,
salary number(10) not null
)


insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
 insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
insert into testdup values(1,'Mukesh Kumar',12,11000);
 insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(2,'Nitin Kumar',13,21000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);
insert into testdup values(3,'Bipin Kumar',14,25000);


Select * from TestDup
output:

ID      Name            Dept    Salary
1    Naween Kumar    10    10000
2    Neeraj Kumar    11    15000
3    Nitin Kumar    12    21000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
1    Mukesh Kumar    12    11000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
2    Nitin Kumar    13    21000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000
3    Bipin Kumar    14    25000


DELETE FROM
           TestDup
WHERE
           ROWID IN
          (SELECT
                   ROWID
          FROM
                    (SELECT
                                ROW_NUMBER()
                     OVER (PARTITION BY id ORDER BY id) rnk
                         FROM
                     TestDup)
            WHERE
                   rnk>1
          );


output:

ID  Name                   Dept  Salary
1    Mukesh Kumar    12     11000
2    Nitin   Kumar       13    21000
3    Bipin Kumar        14     25000