If the earth was stationary, as seen by an observer on earth (an inertial reference frame) a ball thrown straight upwards would go vertically up, then vertically down due to the force of gravity, with no sideways movement. In the inertial reference frame, the angular momentum of the ball relative to the center of the earth zero.
Due to the earth's rotation, as seen by an observer on earth (a non-inertial reference frame), the ball experiences fictitious forces, one of which is the Coriolis force. The Coriolis force appears when an object has a velocity in the rotating frame of reference, here the velocity of the ball relative to the earth. The Coriolis force is $−2m \vec ω × {d^* \vec r \over dt}$ where $m$ is the mass of the object (here, the ball), $\vec ω$ is the angular velocity of the rotating frame of reference, $\vec r$ is the position of the object (in either frame) and ${d^* \vec r \over dt}$ is the velocity of the object in the rotating frame of reference. The Coriolis force, hence the sideways deflection, depends on the latitude where the ball is thrown. In the non-inertial reference frame, the angular momentum of the ball relative to the center of the earth is not zero due to the Coriolis force.
(As an aside, the angular momentum depends on the point about which it is evaluated.)
See a physics mechanics textbook such as Symon, Mechanics, and the question/response @mmesser references in a comment above.