You can easily rename a tablespace by using the ALTER TABLESPACE ... RENAME TO statement as shown in the example below:

SQL> CREATE TABLESPACE my_space

2 DATAFILE '/temp/my_space.dbf' SIZE 10M;

Tablespace created.

SQL> ALTER TABLESPACE my_space RENAME TO your_space;

Tablespace created.

SQL> SELECT TABLESPACE_NAME, STATUS, CONTENTS

2 FROM USER_TABLESPACES;

NAME STATUS  CONTENTS

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

SYSTEM   ONLINE  PERMANENT

UNDO   ONLINE  UNDO

SYSAUX   ONLINE  PERMANENT

TEMP   ONLINE  TEMPORARY

USERS  ONLINE  PERMANENT

YOUR_SPACE  ONLINE  PERMANENT