This article will explain how you can remove messages for your Guestbook on InstantSite
Step 2 of 6
Click on the Edit link.
Step 3 of 6
In the Site map panel, click on the Guestbook page.
Step 4 of 6
Click the check box against the message that you want to delete.
Step 5 of 6
Click on the Remove Selected button.
Step 6 of 6
Click on the OK button to confirm the removal of the message.