The best way is to have a pro rebuild the whole thing, this way they can inspect the bore, seal surface and hone the case so it does not leak again.
Howe, Power Steering components, AGR and a few others can do this.

If you just want to pop that seal out and take your chances, here is how I have seen this done.
With a big drain pan ready, and people very clear, (engine off) remove the snap rig, then start the engine and turn the wheel to lock, the pressure should fire that seal right out.

SD