Unrooting?

Hey guys, I was being stupid and decided to root with Z4Root. Since I'm sending the tablet back to the seller, I want to make sure there's no rooting on the device. So, I pressed the 'unroot' button in Z4Root then it told me that my device now completely had no root. Is this true? Should I do anything else before I restore back to factory settings?
Thanks

 

Please someone help, I got help from the guy who did the main video on how to root it, he told me to unroot from Z4Root, so I did. Then I did a Factory reset. Now once it restarted the touch screen doesn't respond and it just sits there at the unlock screen with the time (that still changes, so it's not frozen or anything) and it doesn't respond to my touch, SOMEBODY PLEASE HELP! I really need help with this since I need to send this Tablet back.