To delete a Facebook group, the group owner must remove every member one by one until only the owner remains. Then, the owner can leave the group, which triggers the permanent deletion of the group.

Steps to delete a Facebook group:

1. Open Facebook on the web or mobile app and go to the Groups section.
2. Select the group you want to delete.
3. Go to the Members tab.
4. Remove each member individually by clicking the three dots next to their name and selecting "Remove member." Confirm each removal.
5. After all members are removed, including any co-admins, you will be the only member left.
6. Find the option to leave the group. Leaving the group as the last member will prompt Facebook to delete the group permanently.
7. Confirm deletion when prompted.

Admins cannot delete a group unless they are the original owner, but they can archive the group instead if they don't want to delete it. Deletion is permanent and cannot be undone, so it’s advised to notify members beforehand if necessary. This process is the same whether on desktop or mobile and requires that all members be removed first before the group can be deleted.