Plugin has broken our website HELP!

We installed this plugin and went to activate it now certain pages on our site are giving us this error:

Fatal error: Cannot redeclare class Contact in /home4/pgshgunm/public_html/RailcarRx.com/wp-content/themes/tourpackage-v1-02/include/plugin/custom-widget/contact-widget.php on line 132

We are also not able to login to the admin dashboard to remove the plugin, any help would be greatly appreciated.

https://ww.wp.xz.cn/plugins/constant-contact-api/