correct procedure to remove interior mirror
 

All over the internet it is mentioned to turn the mirror about 45 degree to remove it. This is not correct, one can break the tabs, causing wobble of the mirror or it can fall off.
This is how to do it

http://i.imgur.com/VeOa20u.jpg
That is from an E36 EBA, but same procedure for E32 and E34.
See here the one from E34 workshop manual
https://www.bmwtechinfo.com/repair/main/741en/images/7411027.jpg

Removal: Pull mirror back off the mirror socket

Installation: Connect mirror base on the mirror socket with an approx. 45 degree turn.
Turn mirror base until it engages on the mirror base.

Mirror removal may vary in different car models according to the setting of that. But, some basic process one has to follow for safe removal of the mirror. In general, We have to first remove the set of screws those are holding the mirror. This will require small or flat blade screwdriver. Once you removed the mirror, you can slide the hammer against the windshield and give the button a sharp whack.

Did you look at the pictures? The base is glued on the windshield on E36, E34, E32 and some other models, there are no screws.