[S1 EP8 SPOILERS!]

After Adam snapped Alastor's cane in half, he managed to escape before he was killed. Charlie and the rest thought he died since they didn't see Alastor distracting Adam anymore.

After Adam and the extermination were defeated, Alastor went to his broken Radio Tower and had a mental breakdown before he returned to the Hazbin crew who were relieved to see he was doing "fine".