A relationship between tables can involve many different fields (read more). You can delete almost any field that is part of a relationship except a reference field. In order to delete a reference field, you must first delete the relationship itself. Then, within the details table, manually delete the reference field.
To delete a field that is part of a relationship:
Open the application which contains the relationship field you want to delete.
Note: If your relationship is between separate applications, open the application containing the Details table. You can only edit a cross-application relationship from within the Details table, not the Master.
Access the relationship.
In the table bar on any application page, click one table in the relationship. Within the menu that appears, select Customize --tablename-- table > Relationships. Locate the relationship you want to change and click its Edit link. The Relationship Properties page opens.
Locate the field that you want to delete, and click its Del
button (see illustration).

Click the Delete this Field button.
Within the confirmation prompt that displays, click Yes, delete the field.
When you delete a field, QuickBase deletes all the data in the field.