This article explains how to disable access the Windows Store in Windows 8.1. The first step is to login to Windows 8.1 using your administrator account. From there you can use one of the below methods:
Method 1 - Using the Registry Editor
Open the Registry Editor. Press Windows key + R to open the Run tab. Type regedit and press Enter. Navigate to HKEY_LOCAL_MACHINE > SOFTWARE > Policies > Microsoft > WindowsStore. Create a New DWORD Value and rename it as RemoveWindowsStore. Double click on this key to edit its value. Type 1 to disable the Windows Store. Save your new settings and close the Registry.
To enable the Windows Store again, simply change the value of RemoveWindowsStore to 0.
Method 2 - Using the Group Policy Editor
Open the Group Policy Editor. Press Windows key + R to open the Run tab. Type gpedit.msc and press Enter. Navigate to User Configuration\Administrative Templates\Windows Components\Store. Double-click on Turn off the Windows Store and select Enabled. Save your settings.
That's it! Access to the Windows Store has been disabled. If a user tries to open the Windows Store, the following message will be displayed:
Windows Store isn't available on this PC. Contact your system administrator for more information