how to get rid of a banner app when accessing a website

Smart App Banners don't use Javascript. It's code embedded in the Web page's header that is recognized by Safari. If you don't want them, try using a different browser like Chrome. Download it in the App Store. But if you use this site enough to care about the search bar, then maybe try the app. You may find it easier to use than the Web site.

The 'x' does work but it is often small and hard to hit. The banner (in Apple's terminology, Smart App Banner) is placed there by the developer of the Web site and its whole purpose is to drive you to their native iOS app. In most cases the app provides a customized and improved experience over using the Web site in Safari. Have you considered installing and using the app instead of the Web site?

And to be clear, as I said the Smart App Banner is placed there by the developer of the Website. There is no way to "turn it off".

You clearly didn't understand my point. It's not 'rogue". It's designed that way to help YOU by pointing out there is an app available rather than using the Web site which is likely not as good an experience.

You clearly don't understand the reasoning behind the original question.

99% of the time, the real website is much more useful than a stupid app that handles one or two basic tasks.

We shouldn't have to close the annoying banner every time we visit a web page.

Just one of a thousand examples: Using an app to reserve a hotel room. You have much more functionality and options from a web site than from ANY travel app that I've ever used. I'm only using that example because I'm traveling now and tried them all again. Most apps are for "priceline people" just get a room, any room, no matter the location or amenities. Most people want more control.

Another reason is being familiar with a website... As most people use a real computer most of the time and a tablet or phone for certain things only while away from their home computer or laptop.

I do use some apps but to really be productive, there usually is nothing better than the real, full website.

I managed to clear this just by closing down the safari app on my iPad. When I restarted it, all my pages loaded with no banner

The solution is to switch to Chrome or Bing or whatever other browser. safari has no option to disable this.

aApple does not make money when you use safari. They make money when you download apps.