Database migration - Simply change connection string?
To ensure writes from the Master are complete, do the following on the Master:

SET GLOBAL read_only = 1;
FLUSH TABLES;
FLUSH LOGS;


Go to the Slave and run the following:

STOP SLAVE;
RESET SLAVE ALL;


Then, make sure there is no Slave setup

SHOW SLAVE STATUS\G


If it comes back with nothing, setup the new connect string and you're done !!!

GIVE IT A TRY !!!