  We study the dispersal of a gaseous disc surrounding a central high-mass
stellar core once this circumstellar disc becomes fully ionized. If the stellar
and surrounding EUV and X-ray radiations are so strong as to rapidly heat up
and ionize the entire circumstellar disc as further facilitated by disc
magnetohydrodynamic (MHD) turbulence, a shock can be driven to travel outward
in the fully ionized disc, behind which the disc expands and thins. For an
extremely massive and powerful stellar core, the ionized gas pressure
overwhelms the centrifugal and gravitational forces in the disc. In this limit,
we construct self-similar shock solutions for such an expansion and depletion
phase. As a significant amount of circumstellar gas being removed, the relic
disc becomes vulnerable to strong stellar winds and fragments into clumps. We
speculate that disc disappearance happens rapidly, perhaps on a timescale of
$\sim 10^3-10^4\hbox{yr}$ once the disc becomes entirely ionized sometime after
the onset of thermal nuclear burning in a high-mass stellar core.
