Hi Peeyush,

Follow below steps.

1. Open UI Page: HR Suspend Dialog

2. In the HTML part of the code replace

<div class="form-group has-error row">

with

<div class="form-group is-required row">

Also,

<label class="col-sm-3 control-label" style="text-align:right" for="suspend_reason">
${gs.getMessage('Reason')}</label>

with

<label class="col-sm-3 control-label" style="text-align:right" for="suspend_reason">
<span class="required-marker"></span>${gs.getMessage('Reason')}</label>

Follow link & replace yourisntancename in the URL & change the sequence for the choices. If sequence column is not present on the list you can add it from List Layout.