In your mysqld.cnf file you can use one of the following:
1- binlog_expire_logs_seconds = 172800
This set it to lower rotate/clean intervals, so it'll reduce the amount of disk space used.
2- skip-log-bin
If you don't use DB replication, you can skip it all together and save all the space. I've disabled it on my servers and don't have binlog taking up space anymore. If you use this, you'll need to manually delete the binlog file from command line or from mysql.