If you are a vista user, here are the steps on how you can uninstall IE8, which we have also covered in the past.
Step 1: Open the Programs and Features applet from control panel.
Step 2: Click on the view installed updates link in the left hand side menu.
Step 3: Once you click on the link, you will see a list of updates that have been installed for Windows Vista and other Microsoft products, the option to uninstall IE8 is clubbed under the group Microsoft Windows, click the text that says Windows Internet Explorer 8.
Step 4: Select the option and click on the uninstall button, this should delete IE8 from your system and restore IE7, you may need to restart the computer for the changes to take effect.