My younger brother lodged his BB-8 head in a helmet, and I just can’t dislodge it.
Show your little brother just how super chill you are by easily solving all his problems.
Just get a normal minifig and pop the head off that. Stick the neck into BB-8 and helmet, and with the extra leverage, you'll be able to snigg-wiggle and separate head from helmet.
Watch the non-delicate surgical procedure here on Youtube. Just skip forward to the 52 second mark of video. Later!