SPWeb.AllowAllWebTemplates Method
Resets the available web templates on the website to the complete set of web templates.
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Available in Sandboxed Solutions: Yes
Available in SharePoint Online
The complete set of web templates is restricted by the language of the website. After calling this method, call the GetAvailableWebTemplates() method to get the complete set of web templates.