Microsoft 365 Copilot includes a memory capability that allows it to retain user-provided preferences or details across interactions when explicitly instructed to remember them. These stored details are referred to as memories and are separate from standard conversation history.

If you previously asked Copilot to remember specific trip-related details, those details are stored as structured memory items. Simply deleting the conversation does not necessarily remove stored memory entries. Likewise, deleting activity history through the My Account portal removes conversation records but does not directly manage structured Copilot memories. Custom instructions define persistent behavioral preferences and are unrelated to trip-specific stored data.

To ensure Copilot no longer retains those trip details, you must delete the stored memories directly within Copilot. Microsoft documentation explains that users can view and manage saved memories and remove them individually to control what Copilot retains.

Therefore, the correct action to ensure Copilot forgets the trip details is to delete the memories.