  Here, we present a detailed theoretical and experimental study on the
pressure induced switching of anomalous Hall effect (AHE) in the triangular
antiferromagnetic (AFM) compound Mn$_3$Sn. Our theoretical model suggests
pressure driven significant splitting of the in-plane Mn bond lengths $i.e.$ an
effective trimerization, which in turn stabilizes a helical AFM ground state by
modifying the inter-plane exchange parameters in the system. We experimentally
demonstrate that the AHE in Mn$_3$Sn reduces from 5$\mu\Omega$ cm at ambient
pressure to zero at an applied pressure of about 1.5 GPa. Furthermore, our
pressure dependent magnetization study reveals that the conventional triangular
AFM ground state of Mn$_3$Sn systematically transforms into the helical AFM
phase where the symmetry does not support a non-vanishing Berry curvature
required for the realization of a finite AHE. The pressure dependent x-ray
diffraction (XRD) study rules out any role of structural phase transition in
the observed phenomenon. In addition, the temperature dependent in-plane
lattice parameter at ambient pressure is found to deviate from the monotonic
behavior when the system enters into the helical AFM phase, thereby, supporting
the proposed impact of trimerization in controlling the AHE. We believe that
the present study makes an important contribution towards understanding the
stabilization mechanism of different magnetic ground states in Mn$_3$Sn and
related materials for their potential applications pertaining to AHE switching.
