  We employ the holographic quench technique to drive Einstein-Maxwell-scalar
(EMs) black holes out of equilibrium and study the real-time dynamics therein.
From the fully nonlinear dynamical simulations, a dynamically unstable
Reissner-Nordstr$\ddot{\text{o}}$m anti-de Sitter (RN-AdS) black hole can be
scalarized spontaneously after an arbitrarily small quench. On the other hand,
a dynamically stable scalarized black hole can be descalarized after a quench
of sufficient strength. Interestingly, on the way to descalarization, the
scalarized black hole behaves like a holographic superfluid, undergoing a
dynamical transition from oscillatory to non-oscillatory decay. Such behaviors
are related to the spectrums of quasi-normal modes of scalarized black holes,
where the dominant mode migrates toward the imaginary axis with increasing
quench strength. In addition, due to the $\mathbb Z_{2}$-symmetry preserved by
the model, the ground state is degenerate. We find that there exists a
threshold for the quench strength that induces a dynamical transition of the
gravitational system from one degenerate ground state to the other. Near the
threshold, the gravitational system is attracted to an excited state, that is,
a RN-AdS black hole with dynamical instability.
