I tried to delete image from api using image id and not deletehash, because when I uploaded image, it didn't give me deletehash. Here is what I tried.
$client_id = "xxxxxxxxxxxxxxxxx";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://api.imgur.com/3/image/pNAHgGq2WvXAUey');
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "DELETE");
curl_setopt($curl, CURLOPT_HTTPHEADER, array('Authorization: Client-ID ' . $client_id));
$result = curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
var_dump($result);
If I browse the image url, it is still there.