Remote host identification has changed : Host key verification failed

When i try to ssh my server, something is wrong, i got warning messages:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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 a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
80:54:8b:9b:39:fb:f1:23:af:0f:4d:af:eb:24:70:44.
Please contact your system administrator.
Add correct host key in /Users/arul/.ssh/known_hosts to get rid of this message.
Offending RSA key in /Users/arul/.ssh/known_hosts:1
RSA host key for 192.168.10.50 has changed and you have requested strict checking.
Host key verification failed.

That messages show up, because RSA host key had change
May be it haven after installed new Operating System
To fix this, i must delete RSA host key for IP 192.168.10.50

vi ~/.ssh/known_hosts

Done, now i can remote with SSH