How to remove an initial value (0) from a "Numeric Entry" field

You can do a work-around, using javascript and jQuery. 

First thing is that you need to import jQuery to the browser. You do this with a javascript trigger:

if (window.jQuery == "undefined") { 
 var head = document.head;
 var script = document.createElement('script');
 script.type = 'text/javascript';
 script.src = 'https://code.jquery.com/jquery-3.6.0.min.js';
 head.appendChild(script);
}

Second you need to add the triggers. If there is only the one numeric input, or of you want to target all input fields in the slide, you can use the code $('input').prop('value', '') .  A better way would be to go through all of them, and check if they have the value "0". Like so:

$('input').each(function() {
   if ($(this).prop('value') == '0') {
      $(this).prop('value','')
   }
}

If the reset button and the input is on the same slide, you can put the triggers in the same button. I.e. Set NumericEntry to value 0 and Execute JavaScript. 

If the input(s) is/are on a different slide you need to set the JavaScript to trigger when the built-in variable "Menu.SlideNumber" changes. This will make it trigger each time the user visits the slide, without having to restart the timeline.

Note that all of this works in Storyline 360, but might not work in other versions.