Downloaded .ics file into my personal calendar

That’s an important clue, if deleting the events removes them from his calendar too, then you likely did not import a static .ics copy. Instead, you may have added or connected to his live/shared calendar with edit permissions.

What you want is to remove or hide the shared calendar from your view.

If you’re using Microsoft Outlook:

• Open Outlook → Calendar
• In the left sidebar, look under Shared Calendars or People’s Calendars
• Find your boss’s calendar
  • Untick it (hides it)
  • Right-click → Remove Shared Calendar

This removes it from your view only, it should not delete his meetings.

Hi!

Welcome to Microsoft Q&A forum.

There is no option in Outlook.com or Outlook on the web to roll a calendar back to a previous day from an .ics file.

The only method is to delete the events manually. In Calendar, change its view into a list-style view (such as Agenda or Week view) and find the events that have been imported using the .ics file. Then, you can delete those events by selecting them one by one. Lastly, If the imported items are easy to identify (for example, you can check it from your boss, or all within a certain date range), use search and delete them in batches.

There is no option in Outlook.com or Outlook on the web to roll a calendar back to a previous day or automatically undo a bulk import from an .ics file. The imported events must be removed from the calendar.

Because an .ics import adds events directly into an existing calendar (such as a personal calendar), the practical options are:

1. Manually delete the imported events
   • In Calendar, switch to a list-style view (for example, Agenda or Day/Week view) and locate the events that came from the .ics file.
   • Select each unwanted event and delete it.
   • If the imported items are easy to identify (for example, all from your boss, or all within a certain date range), use search and delete them in batches.
2. If the events were imported into a separate calendar
   • If, during import, a new calendar was chosen instead of the main one, simply remove or hide that calendar:
     • In the left pane under My calendars, right‑click the imported calendar and remove it from view (or delete it, if available).
3. Use sharing or subscription instead of importing next time
   • Instead of downloading and importing an .ics file, use sharing or subscription so your boss’s calendar stays separate and read‑only:
     • Your boss can publish or share the calendar so it appears as an additional calendar in your view, rather than merging into your personal calendar.
     • In Outlook.com/Outlook on the web, an ICS link can be used to subscribe so the calendar shows alongside your own and updates automatically, without modifying your personal calendar.

There is no built‑in feature to revert the entire personal calendar to a previous state or to “delete everything from today” only if it came from a specific .ics import. Deletion must be done by selecting and removing the unwanted events.

References:

• Add a calendar in Outlook.com or Outlook on the web
• Share your calendar in Outlook.com
• Share your calendar in Outlook on the web