Dropping partition did not free up space

 I just dropped two partitions in a table.alter table SNG.TIMELINE_COLLECT drop partition P2010_09;

alter table SNG.TIMELINE_COLLECT drop partition P2010_10;

The database is on ASM. I need to claim the space back to ASM. There are two tablespaces associated with the two partitions. They are

TIMELINE_COLLECT_D_P2010_09 and TIMELINE_COLLECT_D_P2010_10.

Should I drop them to claim back the space? it looks like the tablespaces have 49MB out of 2GB.

But there is no table or index in those tablespaces.

What is the best way?

Thank you.