In the latest version downloaded from https://github.com/essentials/Essentials/releases/tag/gm-final at time of posting this, the group manager command /mangdeli fails to delete inheritance that was added to a group using the /mangaddi.
Steps to reproduce:
1 - create new group ei. pro: /mangadd pro
2 - add default group inheritance to pro: /mangaddi pro default
3 - remove default group inheritance from pro: /mangdeli pro default