Please provide more information in the form of screenshots of the page in the modeler, the issue that is occurring from the browser, etc. otherwise it will be really difficult to help you troubleshoot this.
One thing that comes to mind that I've encountered before:
Does the page start with a LayoutContainer? I've had occassions where pages immediately had a DataGrid or DataView on it, causing similar scrollbars to appear. The solution in such cases was to wrap the top element with a LayoutContainer full width.