UEFI / Secure Boot - A way to disable booting from CD

I have a bunch of Dell Latitude E6430's with UEFI and Secure Boot enabled. They are running the latest A18 bios update.

Is there any way to disable booting from a CD? I just put in a CD, press F12 and it appears as an option. If I then go in to Setup and uncheck it, all I have to do is take out the CD and put it back in and the option will come back checked.

I don't currently have other Dell computers that are UEFI capable to test to see if this is an issue with this specific model or just UEFI on Dells in general work this way.