How do we clear all the data?

There 2 subdomains we are using the membership plugins for. The first time I install it on the first subdomain, it seems I made an error in some of the settings. So, I wanted to start all over again. I deactivated the plugin and deleted it. When I re-install either via WPMU Dashboard, or FTP or through Plugin Upload of WP, the settings and membership we created is still there. The data we input doesn't get cleared. How do we clear the data?