Undo tablespace full, how to free it My undo tablespace is full after some modifications. Las column is % of space used.

xxx_undo_01.dbf UNDO    2147483648  16777216    2048    2032    16  0,78    99,22

Now i cannot execute any query according to this. How can i free the undo tablespace ?

Thanks in advance.
You can execute below query.

DROP TABLESPACE xxx_undo_01 INCLUDING CONTENTS AND DATAFILES;