An app for welcome message broke my site, the message refuse to go after uninstall

an app for welcome message broke my site, the message refuse to go after uninstall, just take a look at https://quiztablet.com/?ptype=login&page1=sign_in&emsg=1
the problem is the welcome message at the top of the header. i want it totally removed.

The problem is i didnt realize it was still there, until i noticed a large number of bounce rates, on probing, it was this wicked app that refuse to stop injecting bad welcome messages.