How to empty an input type="number" in js?

You have to use value

document.getElementById("elIdDelInput").value = "";

greetings

A quick and short way would be this ... assign an ID to your input:

<input type="number" id="input_vaciar" value="12312313"/>

And then you can empty it like this:

$('#input_vaciar').val('');

And if you need to save some specific data after doing an action, it would be like this:

$('#input_vaciar').val(new_val);

(where new_val can be a data that you set so raw or can be a variable that contains a numeric value as a result of X action)