Don’t Forget Your Embeddings: Robust Knowledge Erasure via Precise Editing of Embeddings

Clara Haya Suslik, Or David Shafran, Mor Geva


Abstract
As language models are increasingly deployed in real-world applications, the ability to erase specific knowledge from them becomes critical for safety and compliance. Prominent methods seek persistent removal by updating the model’s parameters, yet the target knowledge often can be recovered through adversarial prompting or relearning. In this work, we hypothesize this limitation stems in part from existing methods overlooking the embedding layer. To address this, we introduce EMBedding ERasure (EMBER), a plug-n-play erasure module that leverages Sparse Matrix Factorization for precise erasure of concept-related features from token embeddings. Through comprehensive evaluations across diverse concepts on Gemma-2-2B-it and Llama-3.1-8B-Instruct, we find that augmenting existing methods with EMBER consistently improves erasure efficacy and specificity across task formats, with minimal coherence loss. Moreover, EMBER dramatically improves robustness to relearning, reducing regained accuracy by up to 50%, limiting it to 35% on Llama compared to 70%–76% for prior methods. Further analysis shows that the coherence cost is localized, affecting only a small set of concept-exclusive tokens. Our work establishes that precise embedding-level intervention is necessary for robust concept erasure, and demonstrates that existing methods can benefit from such augmentation.
Anthology ID:
2026.findings-emnlp.2091
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
44523–44554
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2091/
DOI:
Bibkey:
Cite (ACL):
Clara Haya Suslik, Or David Shafran, and Mor Geva. 2026. Don’t Forget Your Embeddings: Robust Knowledge Erasure via Precise Editing of Embeddings. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 44523–44554, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Don’t Forget Your Embeddings: Robust Knowledge Erasure via Precise Editing of Embeddings (Suslik et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2091.pdf