Can’t delete social chat plugin

I am having exactly same issue as the link below, on mobile version

https://ww.wp.xz.cn/support/topic/whatsapp-button-wont-disappear-after-deactivating-plugi/

Deactive the plug in, the button still show on mobile

Delete the plug in, the button is gone but there is Whatsapp writing below footer

The page I need help with: [log in to see the link]