Hello Michael,
You may clear all sessions (this will sign all users out, drop all stored carts and remove other session data) as follows:
Code:
DELETE FROM xcart_sessions_data;
DELETE FROM xcart_session_history WHERE dest_xid NOT IN (SELECT sessid FROM xcart_sessions_data) AND xid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_packages_cache WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_shipping_cache WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_users_online WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_ge_products WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_form_ids WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_iterations WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_secure3d_data WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_taxcloud_cache WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);
DELETE FROM xcart_amazon_data WHERE sessid NOT IN (SELECT sessid FROM xcart_sessions_data);