hello we had the following disagreement:
when a zombie dies in order to stab it and permanently kill it do you have to do it in the following action or you have a time limit to stab it until all heroes end their turn?
for example i attacked a zombie with my hero and it died and i had another action but the stake was in another players hand will the other player(which was not adjacent when the zombie died) be able after my turn to come near the dead zombie and stab it or the OL should remove it from the map?
If I understand your question, the English rulebook seems to be clear.
Each time a zombie is defeated, a hero adjacent to the monster may discard 1 ebony stake from his Hero sheet. If he does, that monster is staked and its figure is set aside and cannot be reinforced.
It doesn't take an action to stake a zombie.
The trigger condition is "each time a zombie is defeated", so when a zombie is defeated (typically this will occur after a Hero just performed an Attack action), then at that point if any adjacent Hero has an Ebony Stake, then they can discard it to stake the zombie.
You can't delay this, it happens at the point when the zombie was defeated. If no Hero that is adjacent has an Ebony Stake, then that particular zombie cannot be staked.
The point to note is that you need to determine the trigger condition, in this case it is "each time a zombie is defeated".