We see Forsaken die all the time throughout the history of WoW.
Even Sylvanas dies during the revamped Cata quest lines in Silverpine and she’s a Banshee inhabiting her old body.
Forsaken are more resilient, you’re not going to slow them down much chopping off say an arm or trying to make one bleed out(they don’t “bleed” afaik), but fatal blows to the head will do the trick.