European (especially British) decolonization of Africa was mostly the result of 1) the Atlantic Charter negotiated between FDR and Churchill after WWII when FDR told Churchill to stop that shit, and 2) because Europe’s devastated economy couldn’t afford to maintain their colonies abroad anymore anyway.
I wouldn’t say that Europe did any of this voluntarily, however. they were certainly forced by circumstance, highly pressured by the United States who threatened to withhold fund for post-war relief and rebuilding, and, obviously, mounting unrest in the colonies themselves.