No save button in menus section

My theme (Zerif-Pro) comes with a link called “Sample Page” in the top right hand corner of the screen.
To remove it, I have to go to “menus” and remove it from the custom menu, which is easy enough to do. But every single site I’ve read says there should be a save button on this page, to make sure your changes take effect, but there isn’t?
At no point when I’ve accessed the page has there ever been a “save changes” button.
So no matter how many times I remove the link, it never actually gets removed because I can’t save my changes!

Any idea as to why there is no save button on my screen???