I normally delete the known_hosts file on my machine (not server) when I ssh to a server because the fingerprint has changed. You can delete host’s key as follows.
ssh-keygen -R hostname # Host hostname found: line 6 /Users/benjaminr/.ssh/known_hosts updated. Original contents retained as /Users/benjaminr/.ssh/known_hosts.old
Of course, you don’t want to simply do this unless you are aware something changed.