  Topological modes (TMs) are usually localized at defects or boundaries of a
much larger topological lattice. Recent studies of non-Hermitian band theories
unveiled the non-Hermitian skin effect (NHSE), by which the bulk states
collapse to the boundary as skin modes. Here, we experimentally demonstrate
that the NHSE can conversely affect wavefunctions of TMs by delocalizing them
from the boundary. At a critical non-Hermitian parameter, the in-gap TMs even
become completely extended in the entire bulk lattice, forming an extended mode
outside of a continuum. These extended modes are still protected by bulk-band
topology, making them robust against local disorders. The delocalization effect
is experimentally realized in active mechanical lattices in both
one-dimensional (1D) and two-dimensional (2D) topological lattices, as well as
in a higher-order topological lattice. Furthermore, by the judicious
engineering of the non-Hermiticity distribution, the TMs can deform into a
diversity of shapes. Our findings not only broaden and deepen the current
understanding of the TMs and the NHSE but also open new grounds for topological
applications.
