message: Course update Many
diff: @@ -198,7 +198,7 @@ userSchema.pre('remove', async function () {
  //whitelists
  promises.push(WhitelistUser.remove({uid:localUser.uid}));
  //remove user form courses
  - promises.push(Course.update(
  + promises.push(Course.updateMany(
  {$or: [
  {students:localUser._id},
  {teachers:localUser._id}
  