Is it possible to disable a specific key in OSX?
The only way I am aware of doing this is by using a program which used to be called KeyRemap4MacBook but is now called Karabiner.

Download here: https://pqrs.org/osx/karabiner/

If you would like a walk through, go here: https://www.quora.com/How-does-one-turn-off-their-shift-key-on-a-MacBook-Pro