Why did Hermes killed argus?

Hermes killed Argus, the hundred-eyed giant, to rescue Io, a mortal woman whom Zeus had transformed into a cow to protect her from Hera's jealousy. To distract Argus, Hermes played music and told stories, lulling him to sleep before ultimately slaying him. This act not only freed Io but also showcased Hermes' cunning and resourcefulness as a messenger of the gods. After Argus's death, Hera honored him by placing his eyes on the peacock's feathers.