There are many possibilities how-to setup a mysql replication. Here you will find a hopefully completely How-to really disable it. This is very useful for example if you want to make your slave a primary (standalone) server.

Connect to the mysql shell:

mysql -uroot -p

Commands:

STOP SLAVE;
RESET SLAVE;
change master to master_host=", master_user=", master_password=";

And now some changes to your my.cnf

vi /etc/mysql/my.cnf

*   Comment out every line starting with "master-"
*   add this to your mysqld section

skip-slave-start

Now only a restart of your mysqld should be done.

/etc/init.d/mysqld restart