I have two items, customers did not use. One definitely said "mini" with mesaurments on listing and I recieved a bad review for "too small". The other was chalk they bought 5 of, and returned with a bad review with no explanation why. How can these get removed?
Not at all. We all get bad reviews, that's part of the game.
The best thing you can do with these reviews is taking them as a bonus. Read them and self criticize. What can you do that would have avoided this review? What can you change/adjust, to ensure you wont get another review like that? For example, here it appears size was an issue and the buyer didn't realize how small it is. Adding a picture displaying the item in a hand, for example, would ensure future buyers know exactly what "30mm" or "15cm" or even 3 inches actually look like