You have, because otherwise the login above would have given you the option to create a new user (only one is normally allowed).
You should have, on the SD card in your emonPi, a script called resetpassword.php, which you’ll find in /opt/emoncms/modules/usefulscripts. To get there, you will need to use SSH (or an equivalent application) to access the RPi, and to do that, you need to enable SSH again using the button on the front of the emonPi.
I went through the process with another user a while ago: Emoncms login failure - #4 by Robert.Wall
Try following that and see how you get on.