PURGE BACKUP LOGS
    [ TO id | BEFORE datetime_expr ]

The PURGE BACKUP LOGS statement removes rows from the backup_history and backup_progress MySQL Backup log tables in the mysql database (see Section 1.7, “MySQL Backup Status Logging and Monitoring”). This statement requires the SUPER privilege.

With no TO or BEFORE clause, the statement deletes all rows in the log tables. With a TO clause, the statement deletes rows with a backup_id column value less than the id value. With a BEFORE clause, the statement deletes rows with a start_time column value less than the datetime_expr value. The datetime_expr argument should evaluate to a DATETIME value (a value in 'YYYY-MM-DD hh:mm:ss' format).

Examples:

PURGE BACKUP LOGS TO 143;
PURGE BACKUP LOGS BEFORE '2009-08-31 14:32:19';