Hide or Show Form Pages
When you customize an Outlook form, the procedure that you use for form pages is different from the one that you use for form regions.
Forms customized with form regions
The GetFormRegionStorage method controls which form region is displayed on a form by calling the appropriate form regions storage file (.ofs). Form regions cannot be hidden or shown at run time once the form storage has been returned. For more information, see How to: Create a Form Region and Extending a Form Region with an Add-in.
Forms customized with form pages
In the Forms Designer, click the page that you want to hide or show.
On the Developer tab, in the Form group, click Page, and then click Display This Page.