I cannot access my admin site? Throwing an error code…

I keep getting the same error code, whether I use
http://www.chesinvest.com
http://www.chesinvest.com/wp-admin
http://www.chesinvest.com/wp-login.php

I cannot seem to log into my WordPress admin to address the issue or change the theme.

Fatal error: Cannot redeclare get_users() (previously declared in /home/sellhous/public_html/chesinvest/wp-includes/user.php:635) in /home/sellhous/public_html/chesinvest/wp-content/themes/theme/vivee3/functions.php(1) : eval()’d code on line 1240