Clearing Microsoft Defender Alerts and History

Hi, bill vaccaro

You normally can’t manually delete individual old items from Microsoft Defender’s Alerts & history page, either in the app or on the Defender web portal. The usual option is to open the alert and choose Mark as done, which closes it and moves it to the archived alerts area. Archived alerts may still be viewable from Alerts & history, so this is more like clearing it from active view, not permanently deleting the record.

If the item is from Windows Security > Protection history on the PC, that history is handled differently. It only keeps events for two weeks, then they disappear automatically. You may need administrator rights to view threat details there.

For repeated old Defender alerts on Windows, it is recommended that you avoid deleting Defender system folders unless you are comfortable doing advanced Windows steps. A safer first step is to make sure the alert has been dealt with, mark it done if available, restart the PC, then check again. If the same alert keeps returning after that, use Help and feedback in the Defender app or portal and include the exact alert title and date.

Thank you for your patience in reading, I hope this information has been helpful to you. 

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