@Lisker99 you need a transistor circuit to properly switch the relay off.
The board is isolated from the load circuit but not from the relay supply. Have a look on my sketch at the link above. There you will also find more instructions from the original thread poster how to properly set up a relay circuit. Just follow the links.
Please, just don’t answer the -u was not recognized. What was the issue? If this command does not work then the gpio binding does not work. You will have to write a exec binding and call a Skript with sudo. Which is not the right way, IMHO.
What is the message or behavior for
pi@raspberrypi:~ $ sudo -u openhab gpio -g write 11 1
To be frank you expect help, but offer no information besides. Your suggestion does not work. How should anyone find the culprit in the setup? Try to give proper answers with full explanation what you did and how it responded.
Besides that use code fence for better readability, use the menu at the upper side of the textbox and copy paste you shell lines between the triple quotation marks.
Code goes here