There are plenty of threads on extending the life of the Soviet monster, but far fewer on on killing it off earlier.
So:
Short of full on WWIII, just how soon after the OTL conclusion of WWII can you kill off the SU? And by "killing off": feel free to interpret as you will: I mean effectively to the degree that it is no longer able to competitively function as a counter-balance in the post-war Cold War.