Link to handle $_GET request

If this is in the admin, use the action parameter:

<a href="https://wordpress.stackexchange.com/questions/159391/<?php echo esc_url( admin_url("?action=delete_ticket&ticket_id=$ticket->ID" ) ?>">Delete item</a>

…and then hook appropriately:

function wpse_159391_delete_ticket() {
    if ( isset( $_GET['ticket_id'] ) ) {
        // delete it!
    }
}

add_action( 'admin_action_delete_ticket', 'wpse_159391_delete_ticket' );

For the front-end, you can just append your parameters to the current url and listen out for them on template_redirect:

function wpse_159391_delete_ticket() {
    if ( isset( $_GET['delete_ticket'] ) ) {
        $ticket_id = $_GET['delete_ticket'];
        // delete it!
    }
}

add_action( 'template_redirect', 'wpse_159391_delete_ticket' );

To redirect after processing:

// Get the URL of the current page/post
if ( is_singular() )
    $url = get_permalink( get_queried_object_id() );

// Get custom URL
$url = home_url( 'my/url/path?arguments' );

// Get current URI with removed arguments
$url = remove_query_arg( 'delete_ticket' );

// Get current URI with added arguments
$url = add_query_arg( 'success', 'true' );

wp_redirect( $url );
exit;