When using unlink and rm, files do not show up in the Trash.
However, when using a file manager, they do.
Is there a way to permanently delete a file in Thunar so it does NOT go to the trash ?
Inquiring minds would like to know. 
Usually you obtain this result by using SHIFT+DEL.
If you’re worried about the file still being present on the disk and wish to ensure it is erased in a non-recoverable way, you might wanna check out the shred command.
Thanks, that was simple enuf.