Why did Allah take a covenant from us in the barzakh, then erase that from our memory in this worldly life?

The covenant that Allah Almighty took from the progeny of Adam is the "Fitrah" (innate disposition) inherent in souls, which compels humans to believe in Allah and affirm His Oneness. This covenant has not been erased from memory; rather, it is an enduring spiritual and intellectual necessity. If this covenant were always witnessed and visible, the wisdom of the trial of faith would be nullified.

Scholars have unanimously agreed that the Fitrah upon which every human is born is this covenant and the affirmation of Tawhid (Oneness of God) that Allah took from the progeny of Adam.

As for the statement that we live a second life after the progeny was brought forth and the covenant taken, it is weak. The correct interpretation of His Almighty's saying: (How can you disbelieve in Allah when you were dead and He gave you life? Then He will cause you to die, then He will bring you to life again, and then to Him you will be returned) [Al-Baqarah: 28] is that the first death is non-existence before creation, the first life is creation in this world, the second death is death after worldly life, and the second life is resurrection on the Day of Judgment.