user.schema.ts

var MutationDelete = {
  type: new GraphQLList(UserType),
  description: 'Delete a User',
  args: {
    id: {
      name: 'User id',
      type: new GraphQLNonNull(GraphQLFloat)
    }
  },
  resolve: (root, {id}) => {
    USERs = USERs.filter(function(user) {
      return user.id !== id;
    });
    return USERs;
  }
};