There is no special button to sign out in Macrobond.
By default Macrobond can be used on two machines* (please note that your company might have requested to limit that to only one machine). The account is locked to the first two computers on which it is used. The lock can be reset if you need to move to a different machine. If you need to reset the lock, please contact Support.
You can use Clear Settings Wizard to wipe out your credentials. By default it should be located under C:\Program Files\Macrobond Financial\Macrobond
*machine is here 'one computer in a particular location'