Creating demo accounts for WHM & Cpanel.

ouch

this is very possible -
but it is not suggested.

The cpanel demo can be a security risk

http://demo.cpaneldemos.com:2082/frontend/x3/index.html
is a good place to send clients

http://www.cpaneldemos.com/pricing.html

not a bad cost to ensure your server is safe...

Now - if you still want to do this -

http://www.cpanel.net/docs/whm/

search for demo

 

Cpanel does have a DEMO feature but as a professional security consultant,
I would strongly advise you to re-consider setting up a DEMO account and
just forget that such a feature exists because it is not recommended!

Demo mode on Cpanel / WHM is not full proof by any means and I can
personally from my own experience think of several hundred of ways to
do very terrible things to any server running a Cpanel demo account.

You would be much better off taking sample screen shots and displaying
the graphics images of those screenshots on an advertisement page
for your services instead of giving out unknown user access.