I'm unfortunately not there physically to help, but my mom has this light switch she needs to remove temporarily and replace the plate. Her "handyman" installed it 'brand new' within the past few years. I told her it looked like it was from the 80s haha. Anyways, she apparently cannot remove the knob for the life of her, shouldn't the knob be able to simply pull off without breaking?
The knob should just pull off, but sometimes they require full chooch. If she breaks it, it's not a big deal. If Habitat Re-Store is a thing near her they usually have a shelf of these knobs for almost nothing. If not the big box stores sell them too, and the lights can be turned on and off without the knob until she can get a replacement.
Back when I worked as a handyman I used the old knobs for many things. Some people get very weird about change. I'd usually ask if they wanted the new one to wedge into their junk drawer, though.