RESET MASTER [TO #]

Deletes all binary log files listed in the index file, resets the binary log
index file to be empty, and creates a new binary log file with a suffix of
.000001.

If TO # is given, then the first new binary log file will start from number #.

This statement is for use only when the master is started for the first time,
and should never be used if any slaves are actively replicating from the
binary log.

URL: https://mariadb.com/kb/en/reset-master/