Huh.. odd, well I guess it's worth trawling through the paperjs documentation but it's possible that after removing it, it's still visible, it's just that it doesn't belong to a group anymore... According to the documentation, it removes it from the entire project, which suggests it should disappear. It does also say that it returns a boolean to say whether it actually did perform the removal or not, so it's probably worth checking that. atleast to debug.