How to turn off a GPS with the "exit" button of igo8

I have a Navigon 2310 gps. I installed the iGo8 navigation software because it is more complete.
But when I press the button "exit" of igo8, the software closes and the GPS restarts. Is it possible to turn off a GPS with the "exit" button?
I searched on the internet which function to add in the file sys.txt. I have not found anything.
Thank you for your help.
Regards,

Are you connected to an external power source or running off the internal battery?

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Whether I am connected to a power supply or in battery. The result is the same. By pressing the "exit" button the GPS Navigon reboots