Reset username, password, login

How to reset username, password, account name,… of emonpi?
I received emonpi from someone who forgot all usernames, password, account name, …
How can I start using the emonpi?
I tried putty to connect via shh to emonpi and used (username) pi and pass emonpi2016 (even raspberry) but access denied. Is there any other possibility?

Kind regards,

The easy, and probably the safest, will be to download the latest SD card image (emonSD pre built SD card Download & Change Log · openenergymonitor/emonpi Wiki · GitHub) and make a completely fresh start. That will lose all the data that has been acquired, but I’m guessing that will be OK with you.