Zoho Trial and user numbers

Hi
I am just signing up for the free trial of Zoho.

I had understood that I was signing up for max 12 users for 15 days.

But when I got to three reps - it maxed out on me. Now I cant delete the reps I put in to replace them with the three key people I need!

Firstly - what happened to the 12 users and 15 days?
Secondly - why cant I delete a rep?

this is really early days for me - actually - early HOURS!
please help I dont have long to learn this and deploy it.
thanks
Diane Moreton