  Aims. We report theoretical spectral energy distributions (SEDs), Br$\gamma$
line profiles and visibilities for two scenarios that can explain the disk
dissipation of active hot stars an account for the transition from the Be to
the B spectroscopic phase. Methods. We use the SIMECA code to investigate these
two scenarios: the first one where the disk is formed by successive outbursts
of the central star. A low-density region is developing above the star and
slowly grows outward and forms a ring-like structure that will gradually
excavate the disk. The second one, where a slowly decreasing mass loss, for
instance due to a decrease of the radiative force through an opacity change at
the base of the photosphere, may also be responsible for the vanishing of the
circumstellar disk. Results. We obtain that a clear signature of the disk
dissipation following the ring scenario will be the disappearance of the high
velocity tails in the emission lines and a nearly constant peaks separation.
Moreover, we found that following the ring-like scenario the visibilities must
show an increasing second lobe, an increase of the value of the first zero and,
assuming an unresolved central star, a first zero of the visibility curves that
appends at shorter baselines as far as the disk is been excavate. We propose to
use the AMBER instrument on the VLTI to probe if the the ring scenario is the
one that rule the Be phenomenon.
