Ensure it’s not accessible by any clients, if you use a load balancer, you should take it off temporarily.

Connect to the MySQL Server via the command line:

mysql -u root

Stop the replication:

stop slave;
flush tables;

Now is a good time to make any changes you want to.

Resume replication:

start slave;

Check the status to confirm replication is running normally, and in most cases, catching up with the master:

show slave status\G;

If that went well, now’s a good time to put it back on the load balancer.