How do you change the name your iMac or Macbook?

How do you change the name of your Mac or MacBook so that you don't have two iMacs coming up when you try to Air Drop or an inartfully named Mac and Mac(2) to look at everyday? Go to the Sharing Preference Pane in System Preferences and you can change your Computer Name! So irritating that Apple does not answer this question for themselves! You may have to completely get off of iCloud and also disavow Find My Mac for awhile for the system to forget you before you go back with new identity since it uses the computer's system numeric codes to identify, before it uses the new name.