How to uninstall the ntfs-mac software?
It is pretty easy, you need to download again the Trial version of NTFS for Mac (if you do not have it anymore in your Downloads folder).

Now in Finder, go to your Downloads folder and double click on the NTFS for Mac file. The file should be mounted now. You will see that there is a Uninstall NTFS for Mac program, simply double click it.

That's it. For more information you could refer to the user manual, especially the chapter "De-installing the Driver" page 21.