"ADS-B Logger" is an iFly function and not a Stratux function, so it writes its files to your tablet and not the Stratux. So THAT'snot your issue.
The good news is, there's nothing you can do at this point to make it worse. You can't delete the files without accessing the Stratux via wifi or SSH, and you seem unwilling to give SSH a try. So I recommend you learn how to recreate the SD card, and here's why:
Th Stratux is a DIY project. It's gained so much popularity that some people assemble the units at home and sell them online to people that don't want to assemble them themselves. But the whole idea of the Stratux is that you can "Do It Yourself" without knowing Bo Diddly about programming or hardware. Writing a new image to the SD card is simple, once you've done it the first time. At some point you're going to want to upgrade the Stratux software (which is very easy via the Stratux webpage), and occasionally the update is major enough to require a complete disk re-write, in which case knowing how to write the new image to the SD card is a must (OR, you can purchase a new card online and wait by the mailbox until it arrives).
Instructions are here, and a Google search may find a more detailed how-to:
http://stratux.me/