It may be more difficult to find a close button on devices with smaller screens. If you see a message that says “Don’t show more alerts for this webpage” (or something similar), place a check into the box provided. This should stop pop-ups from recurring. [1] X Research source

Try not to click anywhere else on the pop-up. Clicking through a pop-up ad could bring you to an unsafe website.

iOS: Tap the tab icon at the bottom right corner of Safari. When the browser tabs appear, swipe the one that contains the popup ad to the left. Android: Press the square button at the bottom right corner of the screen, then swipe the tab containing the ad to the left or right. Mac & Windows browsers: Click the small X on the tab.

Windows: Press Ctrl+⇧ Shift+Esc, select the web browser, then click “End Task. ” Mac: ⌘ Command+⌥ Option+Esc, select your web browser, then click “Force Quit. ” Android: Press the square button at the bottom right corner of the screen, then swipe all browser windows off the screen. iPhone: Double-press the home button (if you’re using iPhone 6s, 3D Touch press the left side of the screen), then swipe all instances of the browser off the screen. [4] X Research source

This option is called “Content Settings” in iOS.

This option is called “Block Pop-ups” in iOS.