Dismount the external rear mirror support

Does anyone know how to dismount the external rear mirror plinth on an Exige S1.
Any tutorial or instructions available?

Thank you

there is a grub screw that holds it to the windscreen but the piece on the screen is bonded, there maybe some chemical with will loosen the bond, not sure what breaks down glass glue

I would like to place the two gaskets under the plinth without taking apart the door: