You must setup a user in MySQL, if you use % as the host, it will be a wildcard.
I don't recommend this with root, but if you setup users for each DB you NEED to remotely connect to, you can do so with setting up the correct host.
If you don't want to use a wildcard, and I recommend you don't, you will need to know the hostname of where you are connecting FROM.
i.e. your computer = mycomputer.ispname.com
the remote computer (which you intend on conecting TO MySQL) = abc1234remote.remotedomain.com
Then in the host, you would add: abc1234remote.remotedomain.com, unless it uses a dynamic IP (like non-business highspeed).