You'll only need to remove just one of those rabbet grooved Teak moldings. I removed my sliding hatch a few years ago. It wasn't that bad of a job. Be careful when removing the bungs so that the bung holes are nice and round for the new bung replacements.
I used to remove the bungs by cutting the head off a small wood screw and putting it into an egg beater type hand drill and carefully using it as a drill bit in the center of the bung.
The bung usually comes right up. I also use a miniature woodcraft chisel to remove the old bung if the egg beater drill method doesn't work.
I learned this method from a book entitled "Boat Carpentry" by Hervey Garrett Smith. It works most of the time.