Edit file: /application/views/install.php
Find and delete:
----------------------------------------------------
    $("#verify").validate({
            rules: {
                set_envato_user: "required",
                set_envato_license: "required",
            },

            // Specify the validation error messages
            messages: {
                set_envato_user: "We need your envato username to verify purchase",
                set_envato_license: "Enter your envato purchase code here"
            },

            submitHandler: function(form) {
                form.submit();
            }
        });
----------------------------------------------------
Once installed you do not need name and purchase code. Next step 3 to 4.

Or: