No no no that's wrong. The text or item in the clipboard will return 0 only after you reboot your computer or your device, until that is done, whatever is the latest thing which you copied will still be present on the clipboard. Just don't double tap and that "paste" box will not pop up, double tap when you want to paste whatever you have copied to the clipboard.
Perhaps you think that it should be gone because when you actually copy a text to the clipboard, you can only paste it to a file, document or app capable of handling text input, and if the document of file or app doesn't handle text input nothing will be paste, same to other stuff like pictures musics etc.. on your computer, you can only paste them onto document, files, or apps capable of reading them, but if it happens that you can't paste what you copied to the clipboard, it doesn't mean that the clipboard is empty, it will be empty after you have restarted your computer.
Try to copy this text here, open word on your computer and right click and paste in word, close word completely and reopen it and right click and paste again, open note pad and right click and paste there too. That text will not go away until you either copy something new into the clipboard or reboot your computer.