If I do not have any ACTIVE UNDO segment can I drop an UNDO dbf?

If I do not have any ACTIVE UNDO segment can I drop an UNDO dbf? I have flashback off in my DB. I guess if flashback had been on then dropping an UNDO file would have hindered us from flashing back to a time in the past. But with only expired and unexpired undo and with flashback it should be okay to drop an UNDO. Looking for your valueable inputs before I drop or resize them to a smaller value.

   FILE_ID TABLESPACE_NAME                FILE_NAME                                                                        FILE_SIZE_GB AUT

---------- ------------------------------ -------------------------------------------------------------------------------- ------------ ---

         3 UNDOTBS1                       +DB_ORCL_DAT0349/fidgpa1/datafile/undotbs1.271.843152159                                   30 YES