How to remove a field from my form?

The  "Your Name", "Your E-mail Address" and "Your Message" has been OK.

But "E-mail" was added just before the "Submit". Can to remove that?

You can remove the field by opening the form in the Form Builder and then clicking on the field, you will notice a red "X" click there to delete the field from your form: 

I have also checked and you may do the same, the form history, there you will find all the changes and when they were made, I found the field was added yesterday: 

This guide will also help you to check the changes history for your form: 

How-to-view-form-revision-history