There is no special button to sign out in Macrobond.
Since Macrobond can be used on two machines*, 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'