By default, a custom field in Workfront is editable by everyone who has a Plan license with rights to edit custom forms. You can limit these permissions and determine whether users can manage or only view the custom field.
By default, a new custom field has edit permissions, meaning users can see the field and edit its value. But if you don’t want it to be edited or deleted by others, change the permissions on the field.
If you want specific users, teams, roles, groups, or companies to be able to edit or delete the field in the custom form builder, give them manage rights.
All custom fields are created with default sharing of Editable System-Wide. You can bulk edit sharing to remove or change this option in the Fields tab of the Custom Forms section in the Setup area.