With an eye dropper.

Put a bead of water on the seed casing.
That will soften it.
Be patient, it could take hours.

"Gee Mr Science guy, is that what you do?"

Oh heck no!
I usually squeeze it with forceps right at the hinge.
Pops 'em right off with out damaging the sprout.

It's a skill, and takes time and error to do it right
If you only have a few seedlings, I'd go with water and patience.

You can avoid the issue in the future by planting at the proper depth, and pointy end up.

Aloha,
Weeze