The Settings button in Record Working Times is rendered by the WD ALV component usage of WD CATS. In order to hide the button you have to implement a WD enhancement to the initialization of the WD ALV component usage within WD CATS. In this example only the weekly view is covered, implementation is similar for other views. ERP 6.0 EHP6 SPS04 was used as a reference system.
The Settings button is visible by default.
In ABAP Workbench (SE80), select "Web Dynpro Comp. / Intf." from the dropdown, input HRESS_C_CATS as component, expand the Views folder and double click V_RECORD_WEEK. Go to the Methods tab and select Enhance from the toolbar. Input a name and a description to your enhancement. Scroll left in the list of methods and create a Post-Exit method for the method INITIALIZE_ALV. See the attachment for the coding of the Post-Exit method. Save, activate and Test.
The Settings button isn't visible anymore.
I think SAP should introduce an application parameter in the standard WD CATS application so that WD configuration could be used to decide whether the Settings button is visible or not.