i-mscp by default bans a user after 2 invalid login attempts. If you find yourself locked out of the control panel, login to phpmyadmin (usually located at site.com/pma) as root (needs the mysql root password),

Database: i-mscp
Table: login

Find your current ip address.
Identify this ip within the row titled “login”.
Delete the whole row with the ipaddr field corresponding to your ip address, or change lastaccess value.