Cannot delete contacts from Outlook 365 but they are deleted in Outlook Classic

The remaining contacts require Microsoft Support to inspect and repair the Outlook.com account’s cloud contact store because deletion and editing fail in Outlook.com itself and cannot be performed server-side through Microsoft Q&A.

Open an account-level support request

1. Go to Microsoft Support and sign in with the Microsoft account affected by the Outlook.com contacts.
2. Select Microsoft 365 → Outlook, or enter Outlook.com contacts cannot be deleted in the issue box.
3. Choose Contact Support and request browser chat or another offered support method. Microsoft lists live chat with a specialist as an available additional support option.^1^
4. Ask for the case to be escalated to the Outlook.com/People service team for account-level contact-store investigation.

Include this concise case summary:

Contacts remain visible in Outlook.com People and new Outlook. Deleting them returns “Couldn’t delete contact,” and editing reports “Contact Saved” without persisting the change. They have already been deleted in classic Outlook, are absent from the Outlook contact export, and remain after disabling iPhone contact synchronization and testing in an InPrivate browser window. Please inspect the cloud contact store and duplicate-contact index and remove or repair the inaccessible records.

Attach screenshots showing:

• The contact in Outlook.com → People → All contacts
• The “Couldn’t delete contact” error
• The same contact absent from classic Outlook
• If requested, the date/time and time zone of the latest failed deletion

Microsoft Q&A contributors cannot access an account’s back-end contact data; Microsoft Support is the documented escalation route when server-side synchronization or account configuration must be reviewed.^2^

Why the classic/web discrepancy matters

New Outlook and Outlook.com automatically hide exact and subset duplicates. Microsoft documents that deleting a visible record in classic Outlook can cause a previously hidden duplicate to reappear in Outlook.com until all underlying duplicates are removed. Deleting from Outlook.com should remove the contact and its hidden duplicates from all Outlook clients.^3^

In this case, however:

• The documented Outlook.com deletion operation fails.
• Editing also fails to persist.
• The records are absent from the export.
• Browser isolation and source-device cleanup have already been tested.

Therefore, repeating browser cleanup, iPhone sync changes, classic Outlook deletion, or CSV cleanup is unlikely to reach these records. The normal web operation is People → select contact → Delete → Delete, and Outlook.com supports deleting up to 100 selected contacts at once.^4^ Since that supported operation is failing even for individual contacts, include that fact in the escalation.

Do not run the older ContactsCleanup.exe workaround unless Support confirms the records came from Teams mobile device-contact synchronization. Microsoft’s published workaround was specific to that Teams-generated duplicate issue, not WhatsApp/iPhone synchronization generally.^5^

References

1. Contact us
2. All my contacts are missing with the new outlook. How to fix? - Microsoft Q&A
3. [Outlook.com](https://support.microsoft.com/outlook/people/manage-duplicate-contacts-in-outlook)
4. Add, find, edit, or delete a contact in Outlook | Microsoft Support
5. Fixes or workarounds for recent issues on Outlook.com | Microsoft Support