# Open up a terminal session.
# Change to the hidden .ssh folder in the home directory of the user account trying to ssh:
$ cd ~/.ssh/
$ vim known_hosts
# Using the down arrow key, scroll down until you find the line that begins with the computer name or IP address that you are trying to SSH into.
# With your cursor on that line, press the d key twice which should delete the entire line.
# Press Esc, then :wq, then Enter.
# Now you should be able to try the session again, and you will be prompted to add the new key to the cache.