Disable specific past date of date/time field

// Use a 3rd-party plugin like (https://wordpress.org/plugins/custom-css-js/) to inject the below JQuery

jQuery(document).ready(function( $ ){
// This will hide past 10days from WPUF date/time field
  $("#wpuf-date-dob").datepicker( // your date field's id https://prnt.sc/1gjzyg3
         {
           minDate: -10, // increase/decrease pastDate as you wish
           beforeShow: function() {
           $(this).datepicker('option', 'maxDate');
          }
       });
});