Fatal error: Cannot redeclare class Mailchimp_Folders

Fatal error: Cannot redeclare class Mailchimp_Folders in /home/hzorche/public_html/wp-content/plugins/wr-contactform/addons/mailchimp/api/Mailchimp/Folders.php on line 3

That is what I got when I installed the plugin. Now I cannot open my worpress website. http://432hz-orchestra.com/

Any suggestions on how to procede from now on in order to bring the website back?

Regards,

Ivan K. Yanakiev

https://ww.wp.xz.cn/plugins/contact-form-7-mailchimp-extension/