My iMac Sierra a few days ago I updated new security update. When I put sleeping mode automatically turn on after a few minutes. When I shut down, iMac turn on after a few minutes automatically. I just cannot turn off my iMac instead of keeping by plug off from power source. What should I do for to turn off.
iMac, macOS High Sierra (10.13.3), iMac
Do the SMC reset 2-3 times back to back. If that does not work the reset the NVRAM per How to reset NVRAM on your Mac - Apple Support. If the NVRAM reset does not work then restart in Safe Mode per Use safe mode to isolate issues with your Mac - Apple Support
See if resetting the SMC helps ...
Instructions > How to reset the System Management Controller (SMC) on your Mac - Apple Support
I did SMC reset still does not work
iMac OS Sierra
