Reclaim Space in Tablespace using Shrink Command

    SQL> ALTER TABLE TABLE_NAME enable ROW movement;

    SQL> ALTER TABLE TABLE_NAME shrink SPACE;

    SQL> ALTER TABLE TABLE_NAME disable ROW movement;


Benefits regarding to Oracle Documentation :

    Full table scans will take less time (a table scan will always scan up to the HWM even if space is not used)
    Better index access takes place because of a smaller B-Tree
    Space is freed up for other database objects
    Space below the HWM is released and the HWM is moved down