A clear icon can be attached to the datetimespinner. Click it to clear the entered value.
<div class="easyui-panel" style="width:100%;max-width:400px;padding:30px 60px;">
<div style="margin-bottom:20px">
<input class="easyui-datetimespinner" value="6/24/2015 17:23:40" style="width:100%;" data-options="
showSeconds: true,
prompt: 'Input date time here!',
icons:[{
iconCls:'icon-clear',
handler: function(e){
$(e.data.target).datetimespinner('clear');
}
}],
label: 'Start Time:',
labelPosition: 'top'
">
</div>
</div>