  Kagome superconductors AV$_3$Sb$_5$ (A = K, Rb and Cs) have attracted much
recent attention due to the coexistence of multiple exotic orders. Among them,
the charge density wave (CDW) order has been shown to host various
unconventional behaviors. Here, we investigate the CDW order by a combination
of both bulk and surface doping methods. While element substitutions in bulk
doping change both carriers and the crystal lattice, the surface doping
primarily tunes the carrier concentration. As such, our results reveal a
two-dimensional phase diagram of the CDW in doped CsV$_3$Sb$_5$. In the lightly
bulk doped regime, the existence of CDW order is reversible by tuning the
carrier concentration. But excessive bulk doping permanently destroys the CDW,
regardless of the carrier doping level. These results provide insights to the
origin of the CDW from both electronic and structural degrees of freedom. They
also open an avenue for manipulating the exotic CDW order in Kagome
superconductors.
