Even if Spin That Wheel is described as a customizable game, you can't adjust the chance to win certain prizes or delete the prizes later after you land on them. The Edit Game tool allows you only to add up to 15 prizes:
If you want, you can add multiple times a certain prize and in this way you will increase the chances to win it. Also, if you want, you can configure the game to delete the prizes after they've been won or increase or decrease the spin duration: