removing useless datafile

	We have a tablespace with 2 datafiles. one of the
	datafile is unnecessary and we like to
	delete it ? how do we go about it ?

	Example : Tablespace : USER
		  Datafile   : /m001/.../USER01.dbf
		               /m001/.../USER02.dbf

 		  We like to remove USER02.dbf from the
		  USER tablespace.

	Thanks.