How do I log into another user's OS from my network OS using terminal? To preface this: I'm sure this has been asked but I don't know exactly what I'm searching for or what terms to use, so I am going to ask here by explaining my situation.

I am logged onto a network OS on a host machine (10.9) and I need to view and edit files on the Macintosh HD that is on this actual host machine. The reason why I need to do this is the user's machine is kernel panicking because of a Trend Micro kext in his OS. Whenever I try to go into the user library on Macintosh HD to delete the plists as well, I get "Permission Denied" even when using sudo. I do have the username and password of the user that I'm trying to edit so my question is: How do I log in, through terminal, as that user to edit things inside that users Library folder? 

Hopefully this makes sense -- if not let me know and I can try to clarify further.

Edit: To further explain myself and why I'm going about it this way is simply because I'm curious. If I boot into safe mode it works just fine as it doesn't load the kext. I'm just wondering how this would be done.
Let's say that the user you are trying to become is 'newuser', we'll use the 'su' command (switch user) like so as follows...

Start the terminal and enter:

sudo su - newuser


When prompted enter YOUR password (not newuser's password)

When done you should be logged in to a terminal window as that user.