There are a variety of reasons unwanted events can appear on your Calendar app. You could've accidently accepted a junk invite, or added the calendar of an ex-coworker, boyfriend/girlfriend, family member and so on. If an unknown event appears on your calendar you can remove it like any event. Here's how:
The stock iOS Calendar app is a great way to keep appointments, set tasks and create reminders, but sometimes the listed holidays can clog up your schedule, especially if you do not celebrate them. Each holiday, appointment, reminder, birthday is marked by a dot making it hard to tell them apart. This can be inconvenient if you're searching your calendar app manually and not using the search function.
Keeping track of appointments, holidays, and other events with the iOS Calendar app is convenient. The iPhone integrates event details such as phone numbers and addresses seamlessly into Calendar, with Siri intelligently adding items based on incoming email and messages. Sometimes a PDF file of event dates, or a schedule printed on paper is the best way to share your Calendar. There's a simple way to quickly print your Calendar data as a PDF directly on iPhone.
Attaching documents to your calendar events is a great way to stay organized because it lets you keep relevant information at your fingertips. For example, if you have a vacation planned you can attach your itinerary, maps, hotel reservations and more, rather than digging through your email, files, messages, etc. If you have a conference call scheduled, you can attach your notes and any other reference materials you might need. It is such a useful feature that Apple added it to Reminders as well in iOS 13.