users_filter.js

const users = [
  {
    Name: 'Ramy',
    City: {
      1: {
        city: 'Zagazig'
      },
      2: {
        city: 'Banha'
      }
    }
  },
  {
    Name: 'Ahmed',
    City: {
      1: {
        city: 'Mansoura'
      },
      2: {
        city: 'Cairo'
      }
    }
  }
];

const filteredUsers = users
  .map(u => {
    // get only the city names of users City object
    const cityNames = Object.values(u.City).map(c => c.city);
    // make a copy of that user, we don't love mutate data.
    // but only update City prop to be city names.
    const user = { ...u, City: cityNames };
    return user;
  })
  // Then we filter users where City have `Zagazig`
  .filter(u => u.City.includes('Zagazig')); // => [ { Name: 'Ramy', City: [ 'Zagazig', 'Banha' ] } ]
console.log(filteredUsers);
// to make sure that orignal data is safe
console.log(users);