Redo logs cannot be altered, they can only be created via the CREATE DATABASE and ALTER DATABASE commands or dropped via the ALTER DATABASE command.
You can force a log switch or checkpoint if needed to ensure proper backups during a hot backup or to ensure proper execution of certain operations such as an Oracle tablespace defragmentation. The ALTER SYSTEM SWITCH LOGFILE command is used to switch log files.
You may also need to perform a manual checkpoint on the database. This is accomplished through the ALTER SYSTEM CHECKPOINT command.
You must have the ALTER DATABASE system privilege to be able to perform any of these operations.