I have seen several questions and answers about changing the EC2 key pair for a running instance. However I am a complete AWS newbie at this point and I can easily stop the
You are sort of out of luck with regards to changing the key pair associated with the instance. What you can do, though, is one of the following:
For future reference, best practice would be to have a common key file that is not accessible to everyone to create EC2 instances, then assign credentials for people to do work on them.