A strange button on phone: Exit the mobile version

Hi

I have a problem with the mobile version:
if I make the window on the desktop smaller it looks perfect

But on my smartphone it looks stange and on the bottom there is an button:
Exit the mobile version - if I click on it then the website looks on the phone good.

But I never addes any extra plugins/button to switch on/off the mobile version on the phones...

FYI: in the TOP I user SmartSlider...

Thx
Robert