I recently purchased my house and am completely new to gardening as I've lived in highrise buildings for most of my adult life. I have these adorable window boxes that I just emptied of the sad and dying flowers. The boxes are metal cages with coco liners. Now that the cold weather is here for the winter, any thoughts on what to do with my window boxes that is relatively easy for a newbie like me?

And if I decide to do nothing until spring, should I leave the soil and coco liner in there or remove everything and discard, leaving the metal cages up looking sad and empty?

Any help, advice, personal stories/experiences would be greatly appreciated!