Recover previous instal

[Norm]

I was trying to install JRE and something went askew, now when I boot 
into the system the system hangs trying to start tomcat.
I decided this was no big problem I would just install a new f 7 version 
on another hardrive.  I am not sure why but the second install of F7  is 
quite different and simply put I don't  like, I woulds like to return to 
the original installed version.  Is there a way to stop the system from 
trying to start an application (in this case Tomcat. using either a live 
cd to access files or from the command prompt using the recovery disk?