Fatal Error, Installing Infinite SEO plugin

I got this error, when I tried to install Ultimate SEO plugin: atal error: Call to undefined function user_can_see_seo_metabox() in /home1/ptsblog/public_html/1001peoplethatsuck.com/wp-content/plugins/wpmu-dev-seo-addon/wpmu-dev-seo-addon.php on line 85

I saw on the thread, that someone also had this problem. He renamed the file, and was able to solve it.

I deleted my file, and I cannot solve the problem. I still do not have access to my dashboard. When I click on dashboard, I still get the error message.

Please help!

Thank you.