http://dev.mysql.com/doc/refman/5.0/en/purge-master-logs.html --> this link will tell you how to delete the logs.
If you want to turn off the logs, then edit /var/mysql/my.cnf on Ubuntu and comment out the following lines
- line starting with log_bin
- line starting with expire_log_days
- line starting with max_binlog_size
expire_log_days will tell you the number of days for which the logs will be kept. If it's value is 2. Then all logs older than 2 days will be deleted.
max_binlog_size is the maximum size of the log file. If a log file reaches this limit, then a new log file will be created and appended to. Note, the old log file will not be deleted unless expire_log_days condition satisfies.