If I use the datetime field, I can set a date, but I can't delete it afterwards
The field definition looks like this:
$fields[] = [
'title' => __('Date-Fields', NAME_SPACE),
'post_types' => ['page'],
'fields' => [
[
'name' => __('End-Date', NAME_SPACE),
'id' => PREFIX . 'event_end_time',
'type' => 'datetime',
'size' => 27,
'js_options' => [
'controlType' => 'slider',
'showButtonPanel' => false,
],
'inline' => true,
'timestamp' => true,
'required' => false,
],
],
];