Track Plan Database

I have an S gauge layout that I downloaded from the Track Plan Database. I like the plan and would like to modify it. However, it appears to be locked somehow even though it is a .rrt file. I’ve tried using select all and then unlock selected items. Is this permanetly locked somehow or am I missing something. Thanks in advance for any help.

This doesn’t sound right. The files should be either a PDF or a JPG. Can you provide the link to where you downloaded this, so I can take a look?