I don't have SolidWorks open now, but I believe that you need to set the location for the "SolidWorks Default Templates" to be the same as your "SolidWorks Templates".
+1 for Jerry's answer. Go to your system options, and about halfway down are the file location settings for default templates.
1. If your templates are stored in the same place as the default templates, why not delete the defaults?
2. If your templates are stored in a different location than the defaults, go to your file location settings, and remove the default locations (where the default templates are stored).
Basically two ways to never use the default templates again.