Issue with uninstalling a plugin/

I am a beginner so please take it easy on me. I Installed the WP eCommerce plugin. I deleted pages that I did not want even though it clearly sates “do not delete this page unless you no what you are doing”. After messing up the settings, I deactivated the plugin and deleted it thinking that if I re-installed it I could start fresh. That did not happen, the plugin is still messed up. I used several plugins to clear the error. Clean option, garbage collector, dbManager, I deleted from my FTP, and then when I went to re=install it, same thing still messed up. How do I restore this plugin as if this was the first time that I installed it.

thanks for your help.