According to the documentation this is how you achieve a full width page:
When you want a page to be full width (i.e with no sidebar) then you need to do the following:
Go to Pages > Add New
Add your title and content
Select the Full Width option which is on the right hand side under Page Attributes → Template.
I am not seeing the Full Width option under Page Attributes > Template. I only see Default Template and Archives.
Is there something I need to do in order to get that option to appear there?