title: How to remove permanently added host from list of known hosts?
body: <p>Currently I'm working on a project hosted by my university. We are using git as version control tool and when I connect to host 1st time it displays the following message:
  "Warning: Permanently added '...' (RSA) to the list of known hosts."</p>
  
  <ol>
  <li><p>What does this exactly means?</p></li>
  <li><p>After the job is done, how can I remove this from the known hosts list? Is there any problem if I don't?</p></li>
  </ol>