You have to remove the plastic trim strips that run the length of the roof on each side of the air conditioner. They simply snap into the aluminum channel. The rivets or screws that hold the interior cover on the unit are underneath the plastic.(mine has screws) Be extremely careful and get someone to help you gently pull the strips down. They are fragile, and allowing them to bend too much will break them. Replacements don't exist. Owning a '69 can be interesting. There are a ton of parts exclusive to that year that can be tough to nearly impossible to find. That broken wing window in your pics is going to be painful. I just spent close to $1,000 to replace one of mine. Spend the money and buy a rock guard, it will save you a lot of heartache in the future.
Unrestored 1969 25' Tradewind
Overkill Tow Vehicle of the Year Award:
1997 Chevy C3500 Crew Cab Dually 6.5L Turbo Diesel