I decided to put this in a separate post from my post about troubleshooting my XFX RX 470. Its just some info that would have been helpful when rolling back AMD drivers.
Often, uninstalling the AMD Install Manger is not sufficient to completely uninstall your drivers. Therefore, I also used the AMD Cleanup Utility. Then, using my integrated graphics, I uninstalled all the drivers for my AMD devices listed under Device Manager.
Be sure to click "Show Hidden Devices" under the View tab in the menu. This will show additional drivers for your devices that have been installed, and will also show any devices that are installed, but not connected to your system. After install, your GPUs may not be immediately recognized by your system. In that case, they could be listed under Unknown Devices in Device Manager. In that case, you have to right click your listed and unknown device and go to Properties > Driver > Update Driver > Browse Computer. Choose the directory where you AMD drivers are installed (same location of your AMD Install Manager files) which is by default in C:\AMD. Delete every driver, hidden and otherwise. Be sure to use integrated graphics for this step.
Also, to prevent AMD Install Manager from automatically updating your drivers from 15.12, be sure to uncheck the Automatically Update to New Drivers box at the bottom of the install window. In order to prevent Windows from installing the newest drivers, go to Control Panel > System and Security > System > Advanced System Settings > Hardware Tab > Device Installation Settings and choose No. This will prevent Windows Updates from updating your AMD drivers.