Question

why is it harder to remove an inner shell electron than a valence electron from an atom

Answer 1

I should think because the valence bonds want to escape and bond more whereas the inner layers are for the most part stable

Answer 2

they're closer to the nuclei....ionization energy is higher. having inner shells and a valence only means that the inner shells are conpletely filled and stable.
valence electrons are easily removed only if the number of electrons is =<3 otherwise, they gain rlectrons.