Domian Mapping Plugin Problem

I installed the plugin and entered the domain to be mapped on the wrong area.. now my site is inaccessible unless I remove the plugin. How can I re-install the plugin then remove the domain I mapped to my main domain and be able to configure the plugin properly.

I am gathering that there is probably a table with that mapped domain name that I can edit and remove it there.. but I have no clue which table that would be or how I would access it..

Your help would be greatly appreciated.