If you want to "safely" test this, you could zip up (i.e. backup) your ~/Library/Application Support/Orion folder, then erase it, test it out, and restore your old profile once you're done.
If you wanted to do the files individually, you want to quit Orion, then backup (and subsequently remove):
~/Library/Application Support/Orion/Defaults/history
~/Library/Application Support/Orion/Defaults/history-shm
~/Library/Application Support/Orion/Defaults/history-wal
Just fully quit Orion before deleting anything, or restoring anything. Then you should be able to test this and see whether it happens without a large history.