Can I delete the contents of some TextEdit Documents (60 GB)? (and how?)
It depends on where they are located and what the contents are. I use DaisyDisk when I have disk space issues on my macbook pro. Disk Inventory X sounds like a similar program. With DaisyDisk you can see what and where the files are located that are taking up so much space. You can download and use the free trial version of DaisyDisk from http://www.daisydiskapp.com/.

Maybe that will allow you to navigate to some of the files taking up so much space so that you can open some of them up to see if they are important or not.

As for how to remove the files:

Once you know the location of the files you can easily remove them from terminal. Just run the following command in terminal.app:

sudo rm -rf /Path/To/FolderToDelete/


That command will remove the FolderToDelete folder and all files inside of it.

Be careful with sudo command. See comments below.