With my HD 7770 on Windows 8.1 64 bit, I had to do the full AMD uninstall.
After that I checked the display driver and it was still using an AMD driver (maybe one that comes with Windows 8.1.). So I uninstalled that too via the Advanced Settings.
It was then using the Microsoft Basic display driver.
I installed the 14.1 beta but noticed during the install it did not mention installing the AMD display driver or the Catalyst Control center.
So (after a reboot I think) I ran it again and sure enough it installed the new display driver.
Tested Mantle in BF4 and it was all working.