Use external hdd or ssd instead. Or if you want to use the sd card then go here: https://gbatemp.net/threads/sdusb-the-modern-way-to-play-wii-u-games-from-sd-at-full-speed.655744/
Either use FTPiiu to manually delete the files from the usb or reformat the stick and redownload the game. It's a fool's errand anyway because you'll probably run into the same issue.
They made an accout just to ask that question. If only there's some kind of search engine on the internet. I could make one, I think I'll call it Ask Jeeves.