Syntax:
STOP SLAVE [thread_type [, thread_type] ... ]

thread_type: IO_THREAD | SQL_THREAD

Stops the slave threads. STOP SLAVE requires the SUPER privilege.

Like START SLAVE, this statement may be used with the IO_THREAD and
SQL_THREAD options to name the thread or threads to be stopped.

URL: http://dev.mysql.com/doc/refman/5.1/en/stop-slave.html

