Archive deals, and remove the ones created by mistake
Deals that no longer matter can be archived with a reason: they leave searches, the pipeline, forecasts and won/lost statistics, stay readable, and can be brought back at any time. A deal created by mistake, such as a duplicate, can be removed altogether so it never skews your numbers. Removal works only for deals that were never won and have nothing linked to them — documents, quotes, contracts, emails, calls; any other deal can be archived instead.
Do it from the deal page, or ask Atomo or an AI assistant connected to Nucleo (it always asks you to confirm first). Archived deals have their own filter in the deal list, removed deals can be restored by an admin from Settings, and the company timeline records who archived or removed a deal, when and why.