Ok, the easiest way to do it with cpanel is this...
Go into the back office of the new dev site you made with thirty bees. Go to the SEO and urls page and change the url to what you want the finished end url to be, like yoursite.com.
The go into the cpanel file manager, find the directory your dev site is in, right click on it, and select move. move it to the / directory. Then go into the / directory in the file manager, you will see things like publichtml, logs, and the directory you just moved. Rename the directory called publichtml to publichtmlold. Then rename your dev site's directory to public_html. That should do you and should only take about 5 minutes.