You can shutdown your Cloud Server from the 1&1 IONOS interface as follows:
You are in the Infrastructure > Server section of the Cloud Panel.
In the list, click the desired server.
Click Turn Off.
Select the desired method:
Software: All running processes will be terminated. Subsequently, the operating system will be shut down and rebooted in a controlled manner. This method will only be available if you have VMWare tools installed.
Hardware: All running processes will be terminated immediately and the server will reboot. This can result in loss of data!
The server shutdown process will begin.