It's fairly easy to remove the screen protector, just be careful not to get any glue on the LCD I accidentally did and I permanently dirtied up my screen even more.
Anyways, supplies needed:
- Microfiber cloth
- Suction cup
- Reasonably strong glue (optional)
- Just turn your calculator with the screen facing up.
- There's adhesive holding the screen protector onto the main case. You may want to heat it up, but it's fairly weak so you may be able to get by without doing that.
- Take a strong suction cup and place it directly on the screen. Pull up until the screen protector comes off.
- Take a microfiber cloth and, making sure it never touches any glue, wipe off the dust.
- Now take the microfiber cloth and wipe off the inner part of the screen protector. When you're finished, don't let the same microfiber cloth touch the LCD.
- When you're done, carefully inspect the screen to make sure nothing got on it. Then replace the plastic screen protector. You may want to replace the adhesive with something stronger so dust never gets in it again. I used superglue but I don't recommend you use that in case you ever need to take the screen off.
I hope that helped!