You can remove the Contact Form in either or both of the two places they typically appear on your website.
To remove the Contact Form from the homepage, log into the sitebuilder and go to Design > under Page Settings, click Home > select the downward arrow next to Contact > select Deactivate.
To remove the Contact Page altogether, log into the sitebuilder and go to Design > under Page Settings, click the downward arrow next to Contact > select Deactivate.