If you haven't set a system-wide email configuration, you are unable to use the password recovery feature - you can preserve your settings if you are comfortable browsing and editing a sqlite database.
http://sqlitebrowser.org/ - this tool will allow you to open and browse/edit the database. Turn off webapp via ssh - (sudo /etc/init.d/gunicorn stop) then download /opt/alarmdecoder-webapp/instance/db.sqlite and open with the downloaded db browser. Open up the user's table, and empty out the password field for the specified user. Re-upload the db.sqlite and restart gunicorn process. You should be able to login with a blank password and then reset your password.
If you aren't comfortable doing this, then you will have to remove the database and set up the webapp again.