How to remove the pop up on my computer of a window in Safari
A window in Safari always pops up on my computer, what should I do to remove it!?
[Re-Titled by Moderator]
Earlier Mac models
Block pop-up ads and windows in Safari - Apple Support describes what to do about popup ads and windows that appear while using Safari.
People tend to describe anything unexpected unwanted or unwelcome a "pop-up" though, so you may need to add some more information regarding whatever phenomenon you want to remove.