How can I disable the Samsung Galaxy s4 standard calendar? Please help. I've spent several hours on this and cannot figure it out. I see that the best answer to this issue is to go to the menu and change settings. If you see the screenshot, there is no menu option as far as I can tell. I have tried using the hidden menu button. Am I missing something?  

I have also tried to disable the app in the app manager menu and continue getting double notifications. Any suggestions? 

Thank you!
You can try deleting all data and cache related to the calendar app. 

Go to Settings > Apps > All apps > Touch the app for which you want to clear data > Clear data

For disabling : 


Activate USB Debugging in Settings > Developers Options. If you can't find it, go to Settings > About device > Tap 7 times to bring the Developers Options. 
Download Debloater from here and install it
Connect the phone to the computer (need Samsung USB drivers installed)
Open Debloater, click on READ DEVICE PACKAGES
Find and select the email package (read carefully)
Click on block. Now the app will not be longer available.