How to unselect all images if an "Image List" type user profile field

Hello People,
I have a simple question (hope it has a simple solution )

I added custom fields to my forums user profiles.
My question is regarding an "Image List" type field.
Once I select one of the images for that field in the user's profile... how do I unselect it without having to select another image?

Thanks and regards,
pablo.barral

You would need to make another image box area that is black.

Firstly make sure it's optional to be filled out so you don't make the mistake with anyone else. Then use a blank 1x1px image.