So I ran out of pepper in one of those "disposable" grinders (the kind "they" want you to throw away and buy another). I had some bulk peppercorns from a grinder I used to have. I had been wondering for a while if removing the top and refilling it was possible. Well, tonight when I finally ran out of the "disposable" one, I decided to try it.
First thought was "can I just pry the top off with a butter knife?" Luckily the answer was, "yes!"
Work your way around the bottom of the grinder top with the knife tip. There's a small lip you'll need to get the top over.
Top is off! Now fill with what ever you need to grind. Pepper, salt, custom blends of spices, etc.!
After filling, place top on and turn over. Press down on the bottom of the bottle and the lip of the glass portion should slip into the plastic top. Not much force is needed.