That our minds are not a unity is one of the basic insights of modern psychology – it is the story Dr Freud was telling, and, although it differs on many of the details, modern cognitive neuroscience says a similar thing. The sense of our selves is not the only thing going on in our minds, psychology says. The mind is an inner world which we do not have complete knowledge of, or have control over.
Fortunately psychology can provide some vital intelligence on how to deal with an unruly mind. Consider the famous "don't think of a white bear" problem, which as it implies involves trying not to think about white bears. Try this yourself, or you can set it as a challenge for a loved one you would like to torment. This problem is a paradox: by trying not to think of a thing you constantly have to be checking if you are still thinking of it – re-invoking precisely the thing you are trying not to think of.
The general solution for the white bear problem is to do something else, to avoid both thinking of the white bear and not thinking of the white bear. For earworms, the solution may be the same. Our inner ear, a vital part of our cognitive machinery for remembering and rehearsing sounds, has become infected with an earworm. This is a part of ourselves which is not under our control, so just sending in instructions to "shut up" is unlikely to be of much help (and has been shown to make it worse). Much better is to employ the inner ear in another task, preferably something incompatible with rehearsing the earworm.
If earworms survive because of their peculiarity, the hook that makes them catch, then my prediction for ridding yourself of an earworm is to sing songs that are similar. If your mind is poisoned by Brittany Spears’ Toxic, for instance, then try singing Kylie Minogue’s appropriately titled Can’t Get You Out Of My Head. By my theory this will erode the uniqueness of the memory habitat that lets the earworm survive. Let me know if it works!