Comprehensive and Detailed Step-by-Step Explanation:Inherited fields in ServiceNow are fields that are part of a parent table and automatically become part of child tables through inheritance. This structure is foundational in the ServiceNow data model, ensuring that child tables maintain a consistent relationship with their parent tables.
Here's why inherited fields cannot be deleted from a child table:
* System Design:ServiceNow employs a table inheritance model where child tables derive fields and properties from parent tables. Deleting inherited fields from a child table would break the integrity of the data model, as those fields are shared across multiple tables.
* Impact on Functionality:Many inherited fields, such as sys_created_on or sys_updated_by, are integral to the functionality of the platform. Removing them could disrupt workflows, reporting, and auditing capabilities.
* Alternative Approach:If you want to hide or restrict access to inherited fields in a child table, you can use ACLs (Access Control Lists) to prevent users from viewing or modifying these fields. Another option is to use UI Policies or Client Scripts to control their visibility on forms.
* Developer Note:Attempting to delete inherited fields violates ServiceNow's core principles of maintaining a robust and unified data structure. The platform enforces these rules to ensure consistent behavior across all tables in the hierarchy.
References:
* ServiceNow Developer Documentation on Table Inheritance.
* Best practices outlined on SN Pro Tips regarding scoped application development and table structures.

You must script and configure all required behaviors Provided link has this statement: Extending an existing ServiceNow table means the new table inherits the parent table's columns as well as its business logic.
The following statements apply when extending an existing table:
The parent table's Access Controls are evaluated when determining access to the new table's records and fields. This is true because Access Control (ACL) rules are inherited from the parent table to the child table, unless the child table has its own ACL rules that override the parent table's rules. ACL rules are used to restrict the access to the data and functionality of the ServiceNow platform based on the user's roles and conditions.
The new table inherits the functionality built into the parent table. This is true because the new table inherits the business logic and the relationships from the parent table, such as Business Rules, Script Includes, UI Actions, UI Policies, and Reference Fields. Business logic and relationships are used to define the behavior and the structure of the data on the ServiceNow platform.
The new table inherits all of the fields from the parent table. This is true because the new table inherits the columns and the attributes from the parent table, such as Field Name, Data Type, Default Value, and Mandatory. Columns and attributes are used to define the properties and the characteristics of the data on the ServiceNow platform.
The following statement does not apply when extending an existing table:
You must script and configure all required behaviors. This is false because you do not have to script and configure all required behaviors when extending an existing table, as some of the behaviors are already inherited from the parent table, as explained above. However, you can script and configure additional or customized behaviors for the new table, such as adding new fields, creating new Business Rules, or modifying existing UI Actions. References: Table Extension, Access Control Rules