@bachvarov: That's because the KFMon uninstaller will uninstall... KFMon
.
That leaves NickelMenu, which you can uninstall by creating a file named .adds/nm/uninstall
If, on the other hand, you want to keep NM and just remove the broken menu entry (I'm, err, no quite sure how you managed to end up with a parsing error, though), just remove .adds/nm/koreader