How to edit core doctypes like DocType or User?

[NCP]

You can customize the doctype but you can’t delete the field from the doctype or change the field type because

How to delete form custom field from the database with linux terminal in erpnext?

Hi @nilpatel42, I understand that you may have specific requirements that involve deleting multiple standard fields. However, it is important to note that deleting standard fields can have unwanted results and may affect the functionality and integrity of the system. It disappoints deleting standard fields to ensure data consistency and avoid potential issues with future updates or upgrades. Instead of deleting standard fields, it is recommended to follow customization guidelines, which allow …

If you want to add the field then you can’t add it via custom field. because “Custom Fields cannot be added to core DocTypes”

frappe/frappe/blob/version-15/frappe/model/__init__.py#L98-L117

You have to make a code for the add custom field in the core doctype when install the custom app.

reference:

frappe/hrms/blob/version-15/hrms/setup.py#L54