I've put together a wagon for a child, but I've messed up something. Now I need to remove a plastic cap that has metal bits inside and that goes over the end of the wheel axle. A spare part of this cap looks like this:
What is this part called and what tool can I use to remove it? As I have a spare part, I don't mind destroying the original cap during removal but if there is a way to remove it without destroying it, I'm interested in knowing as well.
I include as well this pic to show where the cap goes in the wagon: