Db error: duplicate entry for key 'users_email'

I’m newbie in OJS and in web develope.
I downloaded the OJS ojs-3.1.0-1 version. Follows all steps for localhost installation but after press de “Install OJS system” button at the installation page appears this error message: DB Error: Duplicate entry ‘xxxxxx@gmail.com’ for key ‘users_email’.
I’m using XAMPP and created the database previously with phpmyadmin.
I have tried several times but I could not complete the installation, and I can’t find any thread that deals with this topic.
Can anybody help me with this issue?