With the help of Stefan I was able to solve the problem.
Shelly 1 can also be turned on or off using URLs. You need to find out the URL to turn off your shelly 1. For my shelly 1 this URL is http://192.168.0.63/relay/0?turn=off
Open the config of shelly motion -> open the "Actions" tab -> Enable "END OF MOTION DETECTED" and add the URL of your shelly 1 turn off command.