Your best bid is to reorganize the tablespace for following reasons

1. An Object(segment) has multiple extents residing at more then one datafile. Logically Object has realation with tablespace but not with datafile.

2. Oracle doesn't support dropping datafiles ! So even though
you manage to empty a datafile, you can not drop it.

Therefore, it is a good idea to recreate the tablespace
with only needed space. (I guess you want to free up the space) Explore if you can shrink the datafile !