Oracle Table Space Can I drop all files

I am trying drop the temp tables space it has three files

/tmp/TEMPRM/create/TEMPRM/datafile/o1_mf_temprm_t_bw3t4zkp_.tmp
+TEMPDATA/rm/datafile/temprm_tempfile_1.dbf
+TEMPDATA/rm/datafile/temprm_tempfile_2.dbf

Before dropping table space I want to delete all the file, I am able to remove the first two files last one gives the error.

 SQL> SQL> ALTER  TABLESPACE TEMPRM_TEMP DROP TEMPFILE '+TEMPDATA/rm/datafile/temprm_tempfile_2.dbf'
 *
 ERROR at line 1:
 ORA-03261: the tablespace TEMPRM_TEMP has only one file

If it is not allowed to delete all the files in table space, How to clean the table space. ?