How do you reprogram mitel sx-50 for disconnection of trunk lines?

To reprogram a Mitel SX-50 for disconnection of trunk lines, access the system programming mode by entering the appropriate codes on the main console. Navigate to the trunk programming section and locate the specific trunk lines you wish to disconnect. Change the status of these trunks to 'out of service' or 'disabled' as needed. Save the changes and exit the programming mode to ensure the new settings take effect.