The text might be on your master page. If so, Shift-Command-Click to release it, or if it will be the same on all pages, edit it on the master page.
If you are in View -> Normal mode and you turn on View -> Extras -> Show Frame Edges, you'll see all of the text frames. If it has a dotted line for a frame, that means it's on the master page.
Or it could just be locked. Default behavior in the prefs is to prohibit selection of locked objects.