How could you make all your freckles go away?

Yes, through a process known as skin bleaching

The most natural method is through daily application of lemon juice to the skin. Other natural acids may work as well, and there are of course chemical skin peels available as well.

Salicylic acid can also be used (same stuff thats used for wart removal); but its risky to use on the face (if done wrong it can leave minor scarring)

A diet high in citrus fruits has also been known to lighten skin (and freckle darkness) for some people.

If the problem is on going (caused by sun exposure), than the best thing you can do is prevent them: use adequate sun screen (even for short sun exposure) and keep to shaded areas as much as possible (indirect sunlight is still good for you but does less skin damage)

Note: lemon juice and citric acids take a long time to work (weeks or even months) and for some it becomes a constant lifestyle choice to maintain.