The traditional view considered forgetting as a passive process where memory traces gradually fade due to the natural weakening of neural connections. However, studies on olfactory memory in Drosophila have revealed that forgetting is an active process controlled by specific neural circuits. Caenorhabditis elegans is a widely used model organism in neurobiological research due to its relatively simple nervous system. Despite its simplicity, C. elegans exhibits complex behaviors influenced by environmental factors and prior experiences. Similar to Drosophila, C. elegans can actively initiate neural circuits based on the type of memory that needs to be forgotten, which supports using C. elegans as a model for studying forgetting. These characteristics facilitate the identification of genes and pathways involved in forgetting in C. elegans. In this review, we discuss recent advances in understanding forgetting mechanisms in C. elegans through three well-characterized olfactory learning paradigms. The insights derived from C. elegans offer a valuable framework for understanding the molecular and cellular mechanisms underlying forgetting, with potentially broader implications for memory regulation in more complex organisms.