Does what you are thinking about feel good? Do you want to experience this thing that you are thinking about?
I'm guessing not. We tend to put too much focus upon what we don't want to experience. How do you let go of this thought?
Imagine it floating away like a balloon. Then, reach for the next better feeling thought. You will experience a sense of freedom and relief, and will be on the road to manifesting what you truly do want to experience.