How Can I Delete the Default/Installed Document Page Sizes in Options

I have tried searching my computer for these "Document Page Sizes" that are listed in Options...Document...Page...Size.
Is there a way to delete these. I don't need them and don't want them in the list. I have created several custom page sizes and they are always at the bottom of the list.

I joined this forum just to get this question answered.

Thank You

Jim Felder