The appointments or tasks created in the calendar app of the OnePlus smartphone can be deleted at any time if a detail or day has been moved indefinitely.

Depending on whether the appointment has a weekly or monthly recurrence, we will be asked whether only this one appointment or also all subsequent ones should be deleted.

Android 10 | OxygenOS 10.0
Step 1:  Open the  Calendar app
Step 2:  Tap on a  day
Step 3:  Select an  event
Step 4:  Open the  menu
Step 5:  Tap on  Delete
Step 6:  Choose  This event ,  This and following events  or  All events
Step 7:  Confirm with  Delete
  1. Open the Calendar app
  2. Tap on a day
  3. Select an event
  4. Open the menu
  5. Tap on Delete
  6. Choose This event, This and following events or All events
  7. Confirm with Delete

OnePlus Instructions