Action: ALTER DATABASE DATAFILE OFFLINE DROP;

What will you get:

1, ARCHIVELOG Mode: Simply take the datefile offline immediately, need media recovery when you bring it online again;

2, NOARCHIVELOG Mode: Take the datafile offline immediately, and it is possible that you can never bring it online again because of the absent of logfiles. The DROP clause doese not remove the datafile from the database, and the datafile will remain in dictionary with a status RECOVER until you drop the tablespace in which the datafile resides.