how to update array of objects when input is changed

You can track the form values with a single useState() hook.

You can use both input onChange event handlers, and form onSubmit event handler to build a component that behaves like you want.

The following is an example React component with hooks you can take as a starting point to manage your state. Please take it as a template and tweak it as needed to fulfill your actual requirement.

const storedData = [
  { id: 1, name: 'apple', city: 'ban' },
  { id: 2, name: 'mango', city: 'hyd' },
]
let nextId = 3

const MyFormComponent = () => {

  const initialFormData = { name: '', city: '' }
  const [formData, setFormData] = useState(initialFormData)

  const clearFormData = () => {
    setFormData(initialFormData)
  }

  const handleOnInputChange = (event) => {
    const { value, name } = event.target

    // merge previous formData with the new value from input
    setFormData({
      ...formData,
      [name]: value,
    })
  }

  const handleOnSubmit = (event) => {
    // prevent HTML form default handler (navigation, etc.)
    event.preventDefault()

    const { name, city } = formData
    // OPTIONAL: handle form data validations
    if (name === '') {
      // no "name" provided
      alert('Must specify a name!')
      return
    }
    // input1 "name" and input2 "city" are available in formData
    // TODO handle the form data and implement your application logic / update storedData / etc.
    // TODO a rough example below, please tweak it to match your requirements
    const existingEntryByIndex = storedData.findIndex(
      ({ name }) => formData.name === name
    )
    if (existingEntryByIndex >= 0 && formData.city === '') {
      // name exists and city value is empty => delete this entry
      // NOTE: city value can't be null, because it will be always a string. Maybe, you can use "null" string though.
      storedData.splice(existingEntryByIndex, 1)
    } else {
      // name exists and city not empty, or name is new => add a new city
      storedData.push({ id: nextId, name, city })
      nextId++
    }
    // --- end of rough example ---

    // OPTIONAL: clear the form values ->
    clearFormData()
  }

  return (
    <div className={'my-form-container'}>
      <form onSubmit={handleOnSubmit}>
        <input
          type="text"
          name="name"
          value={formData.name}
          onChange={handleOnInputChange}
        />
        <input
          type="text"
          name="city"
          value={formData.city}
          onChange={handleOnInputChange}
        />
      </form>
    </div>
  )

For further reference, you can check the React docs to learn about more techniques and ways to handle form inputs, and events.