Bluetooth icon missing from iMac. How do I connect wireless keyboard
To setup Bluetooth keyboard:


Go to System Preferences app → Keyboard → Keyboard.
Click on Set Up Bluetooth Keyboard... button shown at the bottom.




Now, the Bluetooth icon may have been removed from System Preferences app.



To get the Bluetooth icon back again:


With System Preferences app, click View → Customize... in the Menu bar.





Select the checkbox besides the Bluetooth icon and tap Done button shown in the toolbar.





Voila! Bluetooth icon is back again in System Preferences.