Just pick it up, carry it over to the townie, and let go. Their clothes will appear in your inventory. If you don't have at least a couple of empty slots, it won't work.
To get sunglasses off (if you want to save them just before the mayor retires) you have to replace them with cheap glasses. If you want a cheap shortcut, if they're wearing a one piece outfit and you want it back before they retire, just buy shorts, once you put them on a "free" Tshirt appears with them. Same if you buy just a shirt and replace a one piece outfit, but it looks like they're wearing underpants, it's kinda ugly. For a two piece outfit, you have to replace both parts.
You're welcome, hope it works for you!

Yep, I managed to trade a plain, red T-shirt for a black collared shirt. But the offer when I showed it to the store guy that buys things was $55 for the T-shirt and only $59 for the collared shirt. Still, a profit of four coins though. 😊

You don't have to replace cool glasses with cheap glasses. When you buy a pair of glasses you get a blue case to keep them in. Actually, the case just takes up an inventory slot. If you buy a lot of eyeglasses you can sell the extra cases to the store, but hang on to one case. To remove eyeglasses drop the case onto the mayor or peep wearing the glasses. It may take a couple of tries. If it fails, the case drops to the ground at the mayor's feet (even if you're trying to remove glasses from a peep on the other side of town) and the mayor can pick it up.

Wow, that's cool! Thanks, Aviatrix!

Wow, I did not know that! Thank you!

A good way to make money is to first buy potato, carrot or tomato seeds and plant them. You pay $15 (if you haven't yet lowered the prices) and get 5 seeds. 90 minutes later you can pick them and sell them for $10 each for a total of $50 at the store. Gives you a $35 dollar profit.

Has anyone else discovered the theater? Watch a "movie" get some coins, seeds, furniture or clothes, your choice. You can do this 2 times in a row a few times a day.

I used to be able to change the time on my phone, ahead one hour (leave game open), go to game briefly, go back and reset the time. That would cause the game to act like it was starting a new day with new assignment, new stuff in the cave, new rocks and bugs, etc. Lately I can't get it to work, but you can try.