Here is a quick way to uninstall Windows 7 SP1 :
1. Click on the Windows orb and in search box type the following :
wusa.exe /uninstall /kb:976932
2. This will launch the uninstaller for SP1, click Yes to uninstall, sit back and relax while SP1 is removed.
Windows 7 will reboot a few times in the process of uninstalling SP1.
Alternatively, you can go to Control Panel > Programs and Features, then select the SP1 (KB976932) and hit uninstall but this is a quicker and cooler way.