Naturally out first though to close opened Safari tabs on iPhone or iPad, is to open the multiple tab view on iOS device, then slide to close open pages or tabs one by one. See below screen capture of the opened pages in Safari on iPhone.
From the above screenshot, we can see three opened tabs in Safari for mobile. To close a Safari tab or page, you can simply tap on the X icon on the top left corner of each opened page, or you can slide from right to left to close any selected tab in Safari. It is ok, if you have just opened a few pages in Safari. However if you have opened many pages at the same time, it is boring to repeat the steps to close them one by one.
There are many tricks using Safari on our iOS devices. Some features of Safari are not straightforward at all, so many iPhone iPad users do not know they ever exist. For example, do you know how to delete reading list in Safari on iPhone iPad? If you accidentally deleted any bookmarks in Safari, how to recover deleted Safari bookmarks on iPhone?
How to quickly close all opened Safari tabs on iPhone or iPad?
It is actually very easy. Just long press on the Tabs icon at the bottom right corner of the Safari on your iPhone to reveal the pop-up menu at the lower section. You will have the option to close all tabs.
Update May 2019: this article was originally published in Jan 2015 and has since been updated. in this update, the old method to close all Safari tabs before enabling private browsing was deleted. added the new method to reflect the change in more recent iOS versions.