Remove myopenhab service

We just sold our house, and the Raspberry pi with Openhab, which control the house stays.
I want to create a new myopenhap account and remove the service with my own account from papir ui. How do i remove the service and add another one?

You just need to delete the files /var/lib/openhab/uuid and /var/lib/openhab/openhabcloud/secret (replace openhab with openhab2 if you still use that), then restart OH. This should generate a new UUID and secret that the new owner can use to connect their own myopenhab account.