  The kinetic Sunyaev-Zeldovich (kSZ) effect will be an important source of
cosmological and astrophysical information in upcoming surveys of the cosmic
microwave background (CMB). However, the kSZ effect will also act as the
dominant source of noise for several other measurements that use small angular
scales in CMB temperature maps, since its blackbody nature implies that
standard component separation techniques cannot be used to remove it from
observed maps. In this paper, we explore the idea of "de-kSZing": constructing
a template for the late-time kSZ effect using external surveys of large-scale
structure, and then subtracting this template from CMB temperature maps in
order to remove some portion of the kSZ signal. After building intuition for
general aspects of the de-kSZing procedure, we perform forecasts for the
de-kSZing efficiency of several large-scale structure surveys, including BOSS,
DESI, Roman, MegaMapper, and PUMA. We also highlight potential applications of
de-kSZing to cosmological constraints from the CMB temperature power spectrum,
CMB lensing reconstruction, and the moving-lens effect. While our forecasts
predict achievable de-kSZing efficiencies of 10-20% at best, these results are
specific to the de-kSZing formalism adopted in this work, and we expect that
higher efficiencies are possible using improved versions of this formalism.
