GUI toggle buttons problem

So I have this list of radio buttons that are displayed to the player. The player is allowed to select 3 from the list and move on. So I have them set up as toggle buttons but when I select a 4th toggle, I just can't figure out how to turn off the first selected toggle button. Is there a simple way of just changing the button to display that it's not selected anymore? I've come up with a couple of ways to change it but wanted to know if there were a simpler way of doing this like a simple field to set the max amount.