Firstly, why do you ask?
Having said that.
Simply answer IMO is no. Though many Canon dSLR have interchangeable focussing screens, therefore if the 1DX allows that it will reveal the lower surface of the pentaprism......... but neither that surface or the focusing screen are designed for end user cleaning other than a blower brush ~ other methods at users own risk!
If you simply mean cleaning the eyepiece "window", a microfiber cleaning cloth with a breath of warm air beforehand