You create a new canvas panel which contains all your checkboxes. You flag the “is variable” on the panel and also on your checkboxes, so you can manipulate them from BP. Then you add a new variable to your UI called “Clicked Race” (in my case is a list of races) of type checkbox.
Then for each checkbox you select the “OnCheckStateChange” event.
The red nodes on the left are all the events of the checkboxes. The first thing you do is to set your “Clicked Race” variable to the corresponding check box, then you cycle on the canvas panel children, checking for each one if they are equal to your clicked one. If equal then you turn it on, if not then you turn it off. DONE!
The picture should help you to reproduce it in your project. To get the object == object expression, just type == in the pop up window when you drag the checkbox cast.