It is alien to your past. The death of Jesus destroyed the old man. No wonder He will not remember their sin any more. He destroyed who they were and crucified who they used to be. He tasted death for every man.
Death is the end of a lifetime.
It s the end of all its experiences. He tasted the end of all your past as you. That means, in God s eyes your past is destroyed and you are free from it all. Destroying evidence means that nothing is left to convict a person. Not only was your evidence of sins destroyed, but YOU WERE destroyed on the cross, in Christ, and who you are now is a person who did not exist prior to baptism into that death.