Why echo is not working inside PHP class?

i was coding a delete function called deleteProgram() inside a class and everything is working fine but i want to add some javascript code.

<?php

include_once 'db.inc.php';

class DeleteProgram extends Dbh{

    public function deleteProgram(){
        if(isset($_GET['deleteid'])){
            $id = $_GET['deleteid'];
            $sql = "DELETE FROM tblprogram WHERE id='$id';"; 

            $result = $this->connect()->query($sql);  
            header("Location: ../php/program.php");
            exit();

              
        }
    }
}

$delete = new DeleteProgram;
$delete->deleteProgram();

?>

So, this is what i did. I created a try/catch inside my deleteProgram() function inside the if statement and there i use an echo to run the javascript code. But it didn’t display anything so that is where got stuck.

<?php
echo '<script src="https://unpkg.com/sweetalert/dist/sweetalert.min.js"></script>';
include_once 'db.inc.php';

class DeleteProgram extends Dbh{

    public function deleteProgram(){
        if(isset($_GET['deleteid'])){
            $id = $_GET['deleteid'];
            $sql = "DELETE FROM tblprogram WHERE id='$id';"; 
            try{
                $result = $this->connect()->query($sql);  
                echo '<style>.swal-text{
                    text-align: center;
                }</style>';
                echo '<script>swal("Deleted Successfully!", "Program has been deleted", "success");</script>';
                header("Location: ../php/program.php");
                exit();
            }catch(PDOException $e){
                echo '<style>.swal-text{
                    text-align: center;
                }</style>';
                echo '<script>swal ( "Delete failed!" ,  "'.$e->getMessage().'" ,  "error" );</script>';
                exit();
            }
        }
    }


}

$delete = new DeleteProgram;
$delete->deleteProgram();

?>