Can I reset Webmin user password using SSH

SYSTEM INFORMATION
OS type and version Ubuntu 18.04
Webmin version latest

I read in diffferent places that it bis possible to reset webmin user password using ssh. But nothing works, what is the correct way?

See

https://www.virtualmin.com/documentation/developer/cli/change_password/

Well if I have lost the old password this does not help.
Can I find the webmin users via ssh

Yes, you can change any Webmin user password using webmin passwd command.