To find Morkvarg go to the back of the garden and into a hut:
After you speak with and fight Morkvarg pick up the werewolf meat in the pile near the entrance. Then go into the cave near the hut and fight Morkvarg again:
Afterwards feed him the Werewolf meat, which can be found in the quest items tab, to get rid of the werewolf in the garden.
I don’t understand how that works because he said when he ate his own flesh it would burn like eating fire so how does feeding it to him lift the curse? I have a theory because he fed him willingly and that broke it but I’m not sure?