Delete data that is entered by input

I have the following HTML file where #innUsd I enter the amount of what I want to save in Firebase when I press #sendUsd and this amount is reflected in #amountPyp with the amount I had plus the one I sent him.

    <section id="checkinn">
        <article>
            <h3>Ingresos</h3>
            <form>
                <input type="number" value="0" id="innUsd">
                <input type="submit" value="Enviar" id="sendUsd">
            </form>
        </article>
       <article>
           <h3>Monto en Paypal</h3>
           <span>USD$</span><span id="amountPyp"></span> 
       </article>
    </section>

In my Javascript I have the variable that takes the dollars that Paypal has saved and the button that allows me to make the event I need.

I use the (e) = > as a parameter to use preventDefault () and the theme of the sum of the variables works perfectly together with the update to Firebase.

var montoPyp = document.querySelector('#amountPyp');

btnIngreso.addEventListener('click', (e) => {
e.preventDefault();

let ingreso = parseInt(document.querySelector('#innUsd').value);
let fondo = parseInt(montoPyp.innerText);
let total = ingreso + fondo;

ingreso.value = ''

dbPyp.update({
    monto : total
});

})

My problem is that clicking on the 'Submit' button does not set me up empty, poor input.innerText / HTML, income.value, try to do it by converting income into a string, but I have no case.

I would really appreciate the help :)! Greetings and good start to the year ~