There is no correct way. Just get the shell off and eat it! Although Mamy has a point as to whether we are talking hard or soft since different techniques are employed.
There are no "correct" ways, just more efficient ways.
This is the stuff of insurrection....I prefer to open the little end, but big endians object to this, so I normally keep it secret and only eat boiled eggs privately in a locked room when safe to do so, or in times of danger, in a "egg hole" which I had built into the fabric of my house.
It's turning into the Daily Mail where there is a 'correct' way to do everything! Who will finally decide on the 'correct' way to open a boiled egg? The 'correct' way is the way you do it, surely.