How to change MySql Master-Master Replication to Master-Slave Replication
On a basic level, what you have done is enough, but there is a risk it could be re-enabled by mistake as long as the Binary logs exist on master2.
So, if this is just a temporary thing then running RESET SLAVE will remove the master_log_file and read_master_log_pos values, thus preventing replication from starting again by mistake, but maintaining the other values for future use.
If this is going to be permanent, then RESET SLAVE ALL will remove all the replication information (include host, port, user, password etc).