1)PURGE RECYCLEBIN: To delete/remove objects of current users from the recylebin use PURGE RECYCLEBIN.
Other schema users recyclebin objects will be intact. Command is
SQL>PURGE RECYCLEBIN;
2)PURGE DBA_RECYCLEBIN: To clean up all user's recylebin you can use PURGE DBA_RECYCLEBIN statement.
Only user having SYSDBA system privilege can do this task. Command is simply,
SQL>CONN / AS SYSDBA
SQL>PURGE DBA_RECYCLEBIN;
3)PURGE TABLESPACE tablespace_name: With PURGE TABLESPACE tablespace clause you can purge all objects residing in the specified tablespace from the recycle bin.
To clean up all objects that reside in recylebin of USERS tablespace use,
SQL>PURGE TABLESPACE USERS;
4)PURGE TABLESPACE tablespace USER username: With this clause you can reclaim space in a tablespace for a specified user. The specified user's objects from the specified tablespace recyclebin will be cleaned up.
This operation is useful when a particular user is running low on disk quota for the specified tablespace.
To clean up recylebin of user SCOTT from TABLESPACE USERS use,
SQL> PURGE TABLESPACE USERS USER SCOTT;