How to SSH after change in RSA key?

he RSA host key for 7insights.com has changed,
and the key for the corresponding IP address 8.17.170.226
is unchanged. This could either mean that
DNS SPOOFING is happening or the IP address for the host
and its host key have changed at the same time.
Offending key for IP in /Users/desmond/.ssh/known_hosts:6
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
Trying to start an SSH, the server RSA key has changed, I get this failure message:

The fingerprint for the RSA key sent by the remote host is
........
Please contact your system administrator.
Add correct host key in /Users/me/.ssh/known_hosts to get rid of this message.
Offending key in /Users/me/.ssh/known_hosts:4
RSA host key for <domain> has changed and you have requested strict checking.
Host key verification failed.

How to I reset this so it will work?

Thanks!