[Plugin: Simple Google Sitemap XML] Plugin could not be activated because it triggered a fatal error

Fatal error: Cannot redeclare generate_xmlsitemap() (previously declared in /var/www/vhosts/usjanitorialservices.com/httpdocs/wp-content/plugins/simple-google-sitemap-xml/simple-google-sitemap-xml.php:29) in /var/www/vhosts/usjanitorialservices.com/httpdocs/wp-content/plugins/simple-google-sitemap-xml/simple-google-sitemap-xml.php on line 40