It would be darker at night too.

Destroying the moon would require an enormous amount of energy, and it would not be easy to accomplish it without also wrecking life on earth with the debris.

The "seas" on the moon are likely the result of a very impressive impact sometime in the moon's past, which nearly destroyed it. That might give you an idea of how much energy it would take. You would have to break the substance into pieces and impart enough velocity to those pieces to overcome gravity. Even then it is likely some pieces will remain in earth orbit.

The hollow earth theory is an effort to reconcile observed data with a wrong computation of the so-called gravitational neutral point.

The moon's gravitational strength can measured it on earth with sensitive instruments. Its mass can be computed from this value. Its distance is inferred from its orbital period. It's size is deduced from its distance and appearance. Thus an accurate idea of the moon's mass properties does not require visiting the moon. (In fact the reverse is true.) If the moon were hollow, it would mean that the shell would have to be composed of enormously dense yet strong material.