Tsinghua University study finds AI agents rarely honor forget requests

A new benchmark called BEMULA shows memory systems confirm deletions they mostly never perform Telling an AI agent to forget something turns out to be a lot like telling a toddler to forget where the cookies are. You get a cheerful yes, and the knowledge stays exactly where it was. A preprint from researchers at Tsinghua University, released around October 14, 2026, puts hard numbers on that problem. Across every memory system tested, none handled more than 1.5% of forget requests successfully from start to finish. Most scored 0%. That matters now because AI agents are increasingly built to remember you. They store your preferences, your history, and sometimes your personal details across conversations. The study suggests the delete button on that memory is mostly decorative. Inside the BEMULA benchmark The researchers built a new benchmark called BEMULA to measure whether large language model (LLM) agents can actually unlearn sensitive personal information when a user explicitly asks. The team evaluated six prominent memory systems running on three different backbone LLMs. They also included full-context baselines on two of those models, meaning setups where the model simply sees ...