Sounds like you have an original vintage style. The lower bezel has two holes in it and you can use 90 deg snap ring pliers to remove it.
https://images.homedepot-static.com/...5b-64_1000.jpg
https://www.cjponyparts.com/scott-dr...-1966/p/MSK19/
If its stubborn it probably has Locktite on the threads. Heating it with a heat gun will liquify the Locktite once it hits 650F. A soldering iron will work as well, just place the tip at the mating point of threads and nut and heat three areas around the dia.