UNIX for Dummies Questions & Answers

Being new I had my focus in the wrong place and typed in xterm instead of <If you can't guess, good>.

Can I purge xterm so that this word no longer appears using up or down arrows?

Hmm... You want to get rid of your command history?
There is no real reason you should ever do this, and even if you do, a good admin can still catch what you're doing.
Depending on your shell, look in .history, .sh_history, or .bash_history. You can usually edit this file with a text editor, or null it out. Keep in mind though, that whatever command you used to do this will now show up in your history. And if you're using the bash shell, you have to log out first, log in, then edit, since the bash versions I've seen do not write to a file until the session closes.

Since I can't think of a good reason to be doing this, I'm not going to tell you how to do it without leaving traces...