You can rename a tablespace with alter tablespace  command. See the below example.

set pagesize 200
set lines 200
col file_name for a57

SQL> select file_id,file_name,tablespace_name from dba_data_files where file_id=37;

   FILE_ID FILE_NAME						    TABLESPACE_NAME
---------- -------------------------------------------------------- ------------------------------
	37 /home/oracle/app/oracle/oradata/cdb1/testin1.dbf	    TESTING


--- Rename the tablespace_name from TESTING to PRODUCING;

SQL> alter tablespace TESTING rename to PRODUCING;

Tablespace altered.


SQL> select file_id,file_name,tablespace_name from dba_data_files where file_id=37;

   FILE_ID FILE_NAME						    TABLESPACE_NAME
---------- -------------------------------------------------------- ------------------------------
	37 /home/oracle/app/oracle/oradata/cdb1/testin1.dbf	    PRODUCING

NOTE: SYSTEM and SYSAUX tablespace cannot be renamed.