User Account Control (UAC) is one of those things introduced by Microsoft that are helpful in one sense but then in the other they are completely annoying. This security infrastructure was implemented after Windows Vista, allowing you to monitor the launch of non-native applications.
Most of the windows users simply keep it disabled as you have to bear the pop-up and press Yes every time you run an application. But in Windows 8 disabling UAC will effect metro apps and you will not be able to run them while UAC is disabled.
This issue can be solved by performing a little registry edit so that you can run metro style apps while UAC is turned off.
Step 1: Open registry editor by typing regedit in Run Dialogue box.
Step 2: Navigate to the following key:
There you will find a DWORD named EnableLUA. Double click on it and change its value to 1
You need to reboot your computer in order for these settings to work.
Note that this method may greatly reduce your computer security and may leave it vulnerable. Microsoft by default does not support this feature considering security precautions as third-party unknown apps may run with elevated privileges. So you should consider the effects and security measure that come with disabling UAC in Windows.