LGHD1

Sorry guys I am a newbie to this group and need some help on a 98 GTP 3.8. S/C 4 dr. ! How do you get the rear view mirror off? No hex head I can see??? @ How does the hud unit come up and out ? I have a replacement butI cannot see any bolts/fasteners keeping it in.
Thanks for the help in advance and forgive a 60's guy for not knowing about this new (to me) stuff.
Thanks,LArry.