You are part of the DBA team working for a multinational bank. The team is responsible for performing administrative tasks on the database server located at the home office. The database server at the home office has a production database and a test database named TESTDB. The test database is primarily used for testing database commands and configuration settings befor implementing these settings on the production database. The test database is also used for the development of database applications. You have been asked by the senior DBA to grant the SYSDBA privilege to a new team member， John， so that he can perform some administrative tasks， such as shutdown and startup operations， on TESTDB. You use the password file to configure remote authentication on the TESTDB database. You execute the following statement to grant the SYSDBA privilege to John：  
SQL>GRANT SYSDBA TO john；  
However， you receive the following error：  
ORA-01996： GRANT failed： password file  
’c：\oracle\ora9i\dbs\testdb.pwd’ is full  
Which action should you take to add the user john to the password file without removing any of the existing users？（）