You can edit and delete multiple single events at once (such as the events you created with the season planner) in the web interface. This is not possible in the app.
On the home screen, press 'Edit events' at the top of the page, below the menu as shown below. Here you can select the events you would like to edit, which will then open in a spreadsheet. Here you can also add a deadline responses and a maximum number of attendees.
On the home screen, press 'Edit events' at the top of the page, below the menu as shown below. Mark the events you would like to delete and press Delete at the bottom left corner.
IMPORTANT: When an event is deleted, it's deleted for the whole group and cannot be restored. It is also removed from the attendance statistics.