  The manipulation of topological states in quantum matter is an essential
pursuit of fundamental physics and next-generation quantum technology. Here we
report the magnetic manipulation of Weyl fermions in the kagome spin-orbit
semimetal Co$_3$Sn$_2$S$_2$, observed by high-resolution photoemission
spectroscopy. We demonstrate the exchange collapse of spin-orbit-gapped
ferromagnetic Weyl loops into paramagnetic Dirac loops under suppression of the
magnetic order. We further observe that topological Fermi arcs disappear in the
paramagnetic phase, suggesting the annihilation of exchange-split Weyl points.
Our findings indicate that magnetic exchange collapse naturally drives Weyl
fermion annihilation, opening new opportunities for engineering topology under
correlated order parameters.
