I want to reset EditForm.aspx and NewForm.aspx to default for the list, because confused.
How to solve this problem ?
List -> List Settings -> there is some Info Path forms server settings link that leads to the page where you can remove customization.
Changing default Edit/New pages will not help - you need to modify pages for default content type of this list if you want to go this route.
You can also able to do this in SharePoint without needing SP Designer.
You can also opt to delete the custom form by checking Delete the InfoPath Form from the server.
The ans is collecting from this Reference.