unable to customize

Hi, When I press customize button following message appears. Fatal error: Cannot redeclare sanitize_hex_color() (previously declared in /home/a6591824/public_html/wp-content/plugins/chat/chat.php:2607) in /home/a6591824/public_html/wp-includes/class-wp-customize-manager.php on line 1550 host- 000webhost.com website- dimuthu.netai.net Chat plug in- Chat Lite