I just came across this so I am sharing here. Here is the option
https://eonasdan.github.io/bootstrap-datetimepicker/Options/#ignorereadonly
Here is the code.
HTML
<br/>
<!-- padding for jsfiddle -->
<div class="input-group date" id="arrival_date_div">
<input type="text" class="form-control" id="arrival_date" name="arrival_date" required readonly="readonly" />
<span class="input-group-addon">
<span class="glyphicon-calendar glyphicon"></span>
</span>
</div>
JS
$('#arrival_date_div').datetimepicker({
format: "YYYY-MM-DD",
ignoreReadonly: true
});
Here is the fiddle:
http://jsfiddle.net/matbaric/wh1cb6cy/
My version of bootstrap-datetimepicker.js is 4.17.45