LUNE: Efficient LLM Unlearning via LoRA Fine-Tuning with Negative Examples

Yezi Liu, Hanning Chen, Wenjun Huang, Yang Ni, Mohsen Imani


Abstract
Large Language Models (LLMs) encode vast factual knowledge, yet their inability to selectively forget specific information hinders privacy protection, bias mitigation, and post-deployment correction. We present LoRA-based Unlearning with Negative Examples (LUNE), a lightweight framework that performs negative-only unlearning by updating only low-rank adapters while freezing the backbone, thereby localizing edits and avoiding disruptive global changes. Leveraging Low-Rank Adaptation (LoRA), LUNE targets intermediate representations to suppress (or replace) requested knowledge with an order-of-magnitude lower compute and memory than full fine-tuning or direct weight editing. Extensive experiments on multiple factual unlearning tasks show that LUNE: (I) achieves effectiveness comparable to full fine-tuning and memory-editing methods; and (II) reduces computational cost by about an order of magnitude.
Anthology ID:
2026.findings-acl.816
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
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San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
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Findings
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Publisher:
Association for Computational Linguistics
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Pages:
16560–16576
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https://preview.aclanthology.org/ingest-acl/2026.findings-acl.816/
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Cite (ACL):
Yezi Liu, Hanning Chen, Wenjun Huang, Yang Ni, and Mohsen Imani. 2026. LUNE: Efficient LLM Unlearning via LoRA Fine-Tuning with Negative Examples. In Findings of the Association for Computational Linguistics: ACL 2026, pages 16560–16576, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
LUNE: Efficient LLM Unlearning via LoRA Fine-Tuning with Negative Examples (Liu et al., Findings 2026)
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