I can't speak specifically about your camera, but mine has HIGH ISO NR and LONG EXPOSURE NR -- and each has different settings and restrictions/limitations. On my camera, anything over 1 second is considered LONG EXPOSURE, and anything over 800 is considered HIGH ISO. I assume you've checked your owner's manual for the options you have for these features (read the footnotes, if any -- for example, they may not affect RAW files). They may need to be adjusted. They might to too active, or not active enough.
Assuming you are accessing the card on a computer, and have a file manager that allows for search/list for files, just use a wildcard and select all "*.arw" files. It should just display the ARW files and you can delete them.