UAC (User Account Control) is One of the annoying features of Windows which is popping up and asking permission for about everything.It is to protect windows operating system by preventing unauthorized changes to your system and that require administrator permissions . It is also a security feature that will block malicious software from making key system changes without your permission. However UAC in Windows 7 is less annoying and more friendlier now.To change the UAC notification settings navigate to Start > Getting Started > Change UAC settings.
You can adjust the default level ( notify you when programs try to make changes to the computer) to what your most comfortable with and to completely turn it off slide it down to Never notify.
Click OK to make the change effective.Reboot your PC.
You can also disable UAC with Registry Editor
1.Startmenu->run .Type regedit & press enter key
2.Navigate to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System
3.Locate the following REG_DWORD value:EnableLUA
4.Change the value of EnableLUA to 0.
To suppress the UAC permission prompt dialog,
1.Navigate to the ConsentPromptBehaviorAdmin REG_DWORD value
2.Change value the default value of "5" to "0 " (optional).
3.Exit the Registry Editor and Restart the system