Access the admin for a Limitless LED, MiLight, Easybuld... controller.
Login and change default username / password for the Limitless LED, MiLight, Easybuld, and other like controllers.
You should then be prompted for a username / password which are admin / admin to start. Once logged in you can now change that.
If you don't know the IP, which is probably the case when you first set it up, you can check for it in several ways. I setup aliases in my router each time I setup a new device so I know what one is each new controller because it is the only IP not aliased.
If you do not have an easy way to get the IP then I you can check the various IPs connected to your router by logging into it. This usually shows names associated with each IP. The ones for these controllers are usually pretty odd and stand out. If you think you have one, try using that IP to login by going to that IP in the address bar in your browser. If a login dialog appears, you probably have your controller!
Another option, is to run a terminal command to see the IPs on the network.
For the mac you can use: