mysql - 'Commands out of sync; you can't run this command now' php sql error while executing multiple queries

I want to truncate multiple tables. Below is the code:

$del_all = $conn->prepare("TRUNCATE TABLE students"); //line 214
$res = $del_all->execute();
$del_all->store_result();
$del_all->close();

$del_all_fees = $conn->prepare("TRUNCATE TABLE fees");
$res_fees = $del_all_fees->execute();
$del_all_fees->store_result();
$del_all_fees->close();

$del_all_test = $conn->prepare("TRUNCATE TABLE test");
$res_test = $del_all_test->execute();
$del_all_test->store_result();
$del_all_test->close();

$del_all_jan = $conn->prepare("TRUNCATE TABLE jan");
$res_jan = $del_all_jan->execute();
$del_all_jan->store_result();
$del_all_jan->close();

$del_all_feb = $conn->prepare("TRUNCATE TABLE feb");
$res_feb = $del_all_feb->execute();
$del_all_feb->store_result();
$del_all_feb->close();

$del_all_mar = $conn->prepare("TRUNCATE TABLE mar");
$res_mar = $del_all_mar->execute();
$del_all_mar->store_result();
$del_all_mar->close();

if($res>0 && $res_fees>0 && $res_test>0 && $res_jan>0 && $res_feb>0 && $res_mar>0){
    echo "<div class='w3-panel w3-green w3-display-container' style='width:40%;'>
                <span onclick='this.parentElement.style.display='none''
                class='w3-button w3-large w3-display-topright'>&times;</span>
                <p>All Records deleted successfully</p>
            </div>";
} else{
    echo "<div class='w3-panel w3-green w3-display-container' style='width:40%;'>
                <span onclick='this.parentElement.style.display='none''
                class='w3-button w3-large w3-display-topright'>&times;</span>
                <p>Something went wrong. Records not deleted</p>
            </div>";
}
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There is an error'Commands out of sync; you can't run this command now' in C:\wamp\www\classlearn\delete.php on line 214. I know the simultaneous queries cannot be executed, that's why I putclose() function between two queries and astore_result() after each query. But then also, it is giving the same error. What might be a problem? Please Help. I tried to code in a different way as below:

$del_all = "TRUNCATE TABLE students";

$del_all_fees = "TRUNCATE TABLE fees";

$del_all_test = "TRUNCATE TABLE test";                          

$del_all_jan = "TRUNCATE TABLE jan";                            

$del_all_feb = "TRUNCATE TABLE feb";                            

$del_all_mar = "TRUNCATE TABLE mar";

if($conn->query($del_all)&&$conn->query($del_all_fees)&&$conn->query($del_all_test)&&$conn->query($del_all_jan)&&$conn->query($del_all_feb)&&$conn->query($del_all_mar){
    echo "<p>All Records deleted successfully</p>"
} else
    echo "Failed to delete records";
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Then also it didn't worked.