From the PR update: https://www.anthropic.com/news/updates-to-our-consumer-terms

“If you do not choose to provide your data for model training, you’ll continue with our existing 30-day data retention period.“

From the support page: https://privacy.anthropic.com/en/articles/10023548-how-long-...

“If you choose not to allow us to use your chats and coding sessions to improve Claude, your chats will be retained in our back-end storage systems for up to 30 days.”