[Solved] 2 questions on registration form

1. I want to remove the field "City". How can I do that?

2. I have added Birthday at Custom field, tested the frontend, it works.
Then I change its format from the default %Y-%m-%d to %m-%d, the frontend prompts me "format error".
I think it is about the "date" output of the calendar icon. How can I change that accordingly?

Thanks for your help

1. Via the menu Display>Custom fields. Just unpublish it.

2. So you say that you don't want the year... Then, you don't want a calendar picker. It's normal that it doesn't work. Just change the type to a text input box and enter a default value like that: mm-dd
so that users can replace the values.