I just tried it on a different sim, and it does seem to be related to having the robot arm. For the sim that first experienced the problem, I was able to equip both the arm and the glasses at the same time, but the option to take off the glasses didn't appear in the menu until I'd crafted the arm (not put it on). I'm on a different sim now, and put on the glasses (without a roboarm) and the option to take them off is missing from the menu again (I knew I couldn't have simply overlooked it!).
- I pulled a roboarm from the hidden objects menu and put it in the sims inventory, but the option to take off glasses has not returned to the menu.
- In the second event, I wasn't able to remove the glasses until I'd equipped the roboarm.
- After doing that, I was able to take off and delete the roboarm, without losing the ability to take off the computer glasses. Getting rid of the arm doesn't get rid of the option to take them off, as far as I can tell.
I don't know how the glasses are acquired in normal gameplay, as I pulled them from buy/debug, so perhaps that's part of the reason the option to remove them isn't appearing until the functionality is introduced with the robo-arm. Once the arm is used, it can be removed and sold/deleted and the function of putting on and removing glasses remains.