Reset Js

HTML

<!-- Font Awesome -->
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.11.2/css/all.css">
<!-- Bootstrap core CSS -->
<link rel="stylesheet" href="https://motustrength.it/MDB4.19.1-PRO/css/bootstrap.min.css">
<!-- Material Design Bootstrap -->
<link rel="stylesheet" href="https://motustrength.it/MDB4.19.1-PRO/css/mdb.min.css">

<!-- jQuery -->
  <script type="text/javascript" src="https://motustrength.it/MDB4.19.1-PRO/js/jquery.min.js"></script>
  <!-- Bootstrap tooltips -->
  <script type="text/javascript" src="https://motustrength.it/MDB4.19.1-PRO/js/popper.min.js"></script>
  <!-- Bootstrap core JavaScript -->
  <script type="text/javascript" src="https://motustrength.it/MDB4.19.1-PRO/js/bootstrap.min.js"></script>
  <!-- MDB core JavaScript -->
  <script type="text/javascript" src="https://motustrength.it/MDB4.19.1-PRO/js/mdb.min.js"></script>
  
  
<!----Input Field Bootstrap 4.6.0---->

<div class="input-group mb-3">
  <span class="input-group-text" id="txtfocus">Peso</span>
  <input class="form-control" oninput="javascript: if (this.value.length > this.maxLength) this.value = this.value.slice(0, this.maxLength);" type="number" maxlength="3" id="weight" name"weight1" form="bmrcalc">
  <span class="input-group-text">Kg</span>
</div>

<div class="input-group mb-3">
  <span class="input-group-text" id="txtfocus">Altezza</span>
  <input class="form-control" oninput="javascript: if (this.value.length > this.maxLength) this.value = this.value.slice(0, this.maxLength);" type="number" maxlength="3" id="height" name"height1" form="bmrcalc">
  <span class="input-group-text">Cm</span>
</div>

<div class="input-group mb-3">
  <span class="input-group-text" id="txtfocus">Età</span>
  <input class="form-control" oninput="javascript: if (this.value.length > this.maxLength) this.value = this.value.slice(0, this.maxLength);" type="number" maxlength="2" id="age" name"age1" form="bmrcalc">
  <span class="input-group-text">Anni</span>
</div>

<div...

CSS

/*Arrow of dropdown & Input right*/
.caret {
  margin-left: 10px;
}

.select-wrapper input.select-dropdown {
 padding-right: 15px!important;
}

.select-dropdown.form-control {
  text-align: right;
  margin-right: 10px!important;
  color: #0d6efd;
}

/*Font*/
.select-dropdown.form-control, .label-text {
    font-weight: 500;
    font-size: 15px !important;
}

/*Label Field*/
.label-text {
  z-index: 0;
  position: absolute;
  top: 50%;
  left: 5px;
  transform: translateY(-50%);

}

.group-field {
  position: relative!important;
}

/*Dropdown opened top spacing*/
.dropdown-content.select-dropdown.w-100 {
    top: 42px!important;
}

/*Focus Within for Label & Input*/
.group-field.select-dropdown.form-control:focus-within {
    color: #0d6efd;
    background-color: #fff0;
    box-shadow: none !important;
    font-weight: 500 !important;
}

JavaScript

// Material Select Initialization
$(document).ready(function() {
$('.mdb-select').materialSelect();
});

function resetFields() {
document.getElementById("bmrcalc").reset();  
var selectsex = document.getElementById("select-sex");  
        selectsex.selectedIndex = 0; 
}