Master Logs is MySQL's transactional or redo logs.
Purge Master logs up to a specified time or logfile:
PURGE MASTER LOGS TO 'mysql-bin.010';PURGE MASTER LOGS BEFORE '2003-04-02 22:46:26';
PURGE MASTER LOGS TO 'mysql-bin.010';
PURGE MASTER LOGS BEFORE '2003-04-02 22:46:26';
Delete all binary logs
RESET MASTER;