Once enacted, karma cannot be reversed similar as a flower cannot be reverted to a bud. Everything in domain of God Almighty, field of spirituality was permanent. Reason being everything spiritual is connected to our inner self, the spirit existing in our heart as soul atman.
All inner development, partial kundalini awakening, spiritual progress was permanent and could never be reversed back. Spirituality directly relates to human brain. Once dormant lying portions of brain start activating, they could never be reverted back to their original position.
We cannot reverse karma but we can always neutralize bad karma by indulging in good karma, positive karma all the time. For example if we have a negative karmic debt of -45 then we have to indulge in good karma, positive karma and gain +45 on karmic index. Only then the negative residual balance of karma from present or past lives can be neutralized in totality.
A negative residual balance of karma always results in untold sufferings. For human beings to enjoy a good life full of happiness and pleasure, our indulgence in good karma all the time is necessitated. We just cannot expect mangoes to grow on a guava tree. As our indulgence in karma, accordingly the manifestation!
Prime reason why young children need to be taken care of! They are not aware of laws of karma. Mistaking a snake for a rope by a toddler is nothing new.