Archetype and bootstrap
 

Is there a way to use an archetype to remove a bootstrap ?

I want to remove the cure spell (or inflict spell) from the oracle (and add a bit of choice instead of "all cure spell or all inflict spell"); but since those spells are directly bootstrapped in the oracle class, I don't see how I can remove the spells with an archetype...

Whether something can be suppressed/cancelled/deleted is something you have to ask on a case-by-case basis, rather than asking whether archetypes can do it in general.

In this case, the choice is tied to the positive/negative channeling, and I can't figure out a way to remove it.

You'll need to create a copy of the Oracle, and set up the spells on the copy so that there are more choices available. Sorry.