I don't think one necessarily edits the memory. Memories intrinsically decay over time; each recall is associated with a greater chance of being able to recall it in the future (memorization), with bonuses to spaced out recollections (spaced repetition) and optional userland hinting to the OS (going to sleep while expecting to be tested on something leads to greater retention for the same number of reviews).

In other words, the brain is a cache that implements Least Recently Used eviction.