Payment Status

I know you have answered a similar question before, like over 2 years ago where you wrote you had made this possible in a update. I can find this code in the files but need you help to enter the right values.
I believe this is the code where I am to enter the payment status to be deleted (processing). That means, the entries that haven’t been payed for yet.

$search_critera = array(
			'start_date'     => date( 'Y-m-d H:i:s', 0 ),
			'end_date'       => date( 'Y-m-d H:i:s', strtotime( '-' . $settings['deletionDate']['number'] . ' ' . $settings['deletionDate']['unit'] ) ),
			'payment_status' => null,
		);

What am I to enter under payment_status?

Thanks for your support!