and press the Edit button at the top.
Then the Add Holidays menu appears.
Editing and deleting the added holidays can be done by selecting the items in the Edit Category mode.
Here you can change or delete the color of them.
However, when you use synchronized holidays added to iOS or Google Calendar,
there may be restrictions on editing or deleting them.
If this happens, visit iOS or Google Calendar to edit and synchronize them.
So please try it and ask if you have any difficulties in the process.