How to reset password of rancheros

Hi All,
I have a serious issue:
I wanted to login into my baremetal rancheros installation.
But it keeps on refusing my username password combination.
The docker engine is running already for several years, and im sure i have never changed my password.
How can I reset my password if i am not able to login ?

rancheros version linux x86_64 RancherOS v1.5.6
running on a macmini

btw the machine is running fine. I have quite a lot of dockerclients running on it with a lot of small home automation features. SO i would prefer not to do a reinstall and risk losing anything.