It is not possible to hide the Dependents portlet in the Add New Employee (or any Hire) wizard because the Hire wziard does not support Role-Based Permissions.
Add new hire doesn't respects Role-based Permissions.
Also, hiding the entire portlet with Business Rules is not supported, as it causes system instability and errors (so please do not do that, it will not be supported).
To avoid admins or hiring managers fill in the Dependent's portlet, please create a Business Rule to Raise Message, instructing the operator to skip completing the Dependents Information.
How to raising a message on New Hire screen when hiring manager tries to add Dependent’s information.
Step1: Create a new “MessageDefinition” via Admin Center > Manage Data > Create New "Message Definition".
Step2: Create a Business Rule as per the below definition:
Step3: Add the new Business Rule as an onChange rule for the "relationship-type" field under the "personRelationshipInfo" portlet as shown below in the Admin Center > Manage Business Configuration UI.
Step4: Test the rule works
SuccessFactors Employee Central Business Rule Example Raise Message , KBA , LOD-SF-EC-RUL , Business Rules & Event Derivation , LOD-SF-EC , Employee Central , How To