Where can I see the most recent updated time and the other things list in windows 7 and is there any way to reverse it back once after updating the OS?
Open Control Panel, then Programs and Features, then choose View Installed Updates. From there, you can request to have a selected update uninstalled. You can also do all this from the Windows Update utility. Microsoft's help page is here: http://windows.microsoft.com/en-US/windows-vista/Remove-an-update.