<form action="" method="post">
    <input type="hidden" name="id" value="5">
    <button type="submit" name="deleteUser">Kullanıcıyı Sil</button>
</form>

if (isset($_POST['deleteUser']))
{
    // çalışacak kodlar
}

$site = file_get_contents('http://ip-api.com/json/'.$_SERVER['REMOTE_ADDR']);
$jsonSite = json_decode($site, true);

header('Location:'.$jsonSite['city'].'-gul-satisleri.php');

function post($name, $subName = null)
{
    if ($subName == null) {
        if (isset($_POST[$name]))
            return $_POST[$name];
    } else {
        if (is_array($_POST[$name]))
            return $_POST[$name][$subname];
    }
}

RewriteEngine On

RewriteRule ^([0-9a-zA-Z])-gul-satislari$ gul-satislari.php?deger=$1 [QSA]

<h1><?= @$_GET['deger']; ?></h1>
<hr>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit.</p>