The best way is to replace it. Or rewrite it. I had that problem a while back with an incessant fiddle tune, "Mason's Apron" that I couldn't shake so I decided consciously to change it with another tune and rewrite it as a composite of another tune.

One of the most constructive ways to handle this problem is to write another tune or song.
Or take the one you have rolling around in your head and do what so many songwriters do,
recycle it.