did all the steps many times and still can’t remove the subscribed calendar, i lost all my appointments in my calendar, don’t know what to do more

Hi pipa256,

welcome to the Apple (user-to-user) Community.

Seems the "Related Article" is for iOS 14.6 or later (ie: in 2021)

... wondering which iOS you have installed on your iPhone.

Eg: For iOS16:

How to: "Unsubscribe from a calendar

You can unsubscribe from a calendar you’re subscribed to.

When you unsubscribe, you can also report the calendar as junk.

1. Tap Calendars at the bottom of the screen.
2. Tap  next to the calendar you want to unsubscribe from.
3. Tap Unsubscribe, then Tap Unsubscribe or Unsubscribe and Report Junk.
4. Note: When you tap Unsubscribe and Report Junk, the calendar is reported to Apple as a suspected junk subscription."

Above is from the complete Apple Support article (2023):

Set up multiple calendars on iPhone – Apple Support

All the best:-)

PS: If you have iCloud: Delete a calendar

1. Tap Calendars at the bottom of the screen.
2. Tap  next to the iCloud calendar you want to delete.
3. Tap Delete Calendar at the bottom of the list.

From: Share iCloud calendars on iPhone – Apple Support