[{"_id":"111","email":"michael@gmail.com","username":"michael098","groups":[{"_id":"222","groupName":"family","groupMembers":[{"_id":"333","name":"Liam"},{"_id":"444","name":"Noah"}]},{"_id":"555","groupName":"friends","groupMembers":[{"_id":"666","name":"Oliver"}]}]}]

db.collection.update({"groups._id":"222"},{$pull:{"groups.$[].groupMembers":{"_id":"444"}},})