Using a reaction wheel. https://en.wikipedia.org/wiki/Reaction_wheel https://en.wikipedia.org/wiki/Reaction_wheel Basically, an heavy enclosed wheel that you

Using a reaction wheel. https://en.wikipedia.org/wiki/Reaction_wheel https://en.wikipedia.org/wiki/Reaction_wheel Basically, an heavy enclosed wheel that you use a motor to spin. Because of the conservation of angular momentum, the rocket will spin in the opposite direction (more slowly, because it's (probably) heavier).