How to Create TEMPORARY tablespace and drop existing temporary tablespace in oracle 11g/12c

1. Create Temporary Tablespace Temp

create temporary tablespace temp2 tempfile '/mnt/mnt04/oradata/temp01.dbf'size 2000M; 

2. Move Default Database temp tablespace

ALTER DATABASE DEFAULT TEMPORARY TABLESPACE temp2;

3. Make sure No sessions are using your Old Temp (TEMP) tablespace

   a.  Find Session Number from V$SORT_USAGE: 
       SELECT USERNAME, SESSION_NUM, SESSION_ADDR FROM V$SORT_USAGE; 

SQL> SELECT USERNAME, SESSION_NUM, SESSION_ADDR FROM V$SORT_USAGE;

USERNAME                       SESSION_NUM        SESSION_ADDR
----------------------------------------------------------------------------- 
SYS                                       45684           0000000CE2EA7CC8

   b.  Find Session ID from V$SESSION:

       If the resultset contains any tows then your next step will be to find the SID from the V$SESSION view. You can find session id by using SESSION_NUM or SESSION_ADDR from previous resultset.

       SELECT SID, SERIAL#, STATUS FROM V$SESSION WHERE SERIAL#=SESSION_NUM;
       OR
       SELECT SID, SERIAL#, STATUS FROM V$SESSION WHERE SADDR=SESSION_ADDR; 
OR
SQL> SELECT b.tablespace,b.segfile#,b.segblk#,b.blocks,a.sid,a.serial#,
a.username,a.osuser, a.status
FROM v$session a,v$sort_usage b
WHERE a.saddr = b.session_addr;

c.  Kill Session:

Provide above inputs to following query, and kill session’s.
SQL> alter system kill session 'SID_NUMBER, SERIAL#NUMBER';
For example:
SQL> alter system kill session '633,45684';

4. Drop TEMP tablespace

drop tablespace TEMP including contents and datafiles;

5. Recreate Tablespace Temp

CREATE TEMPORARY TABLESPACE TEMP TEMPFILE  '/mnt/mnt04/oradata/temp_01.dbf' SIZE 1G AUTOEXTEND ON NEXT 1G MAXSIZE 32767M;

6. Move Tablespace Temp, back to new temp tablespace

ALTER DATABASE DEFAULT TEMPORARY TABLESPACE TEMP;

7. Drop temporary for tablespace temp

DROP TABLESPACE temp2 INCLUDING CONTENTS AND DATAFILES;

No need to do shutdown when drop temp tablespace and the recreate it. If something happen with temp tablespaces e.g. : crash, corrupt, etc. Oracle database will ignore the error, but DML (insert,update,delete) and SELECT Query will suffer.