The D5 series of printers will no longer ship with the Lower Z-Axis Endstop switch. This component has been discontinued due to it being unnecessary for normal operation of the printer.
If you are using the correct dimensions in your Wanhao Maker profile the lack of this endstop switch should not be an issue as the slicer will warn you of tall models that would allow the build plate to crash into the bottom of the frame. If you happen to load a model that is too tall for the build plate the software will prompt you with a warning message and give you the option to automatically re-size your model. You can also scale down the model manually using the SCALE button at the top of your Wanhao Maker user interface.
You can edit your Wanhao Maker profile by going to EDIT > SETTINGS on the Wanhao Maker user interface.
Your settings should look like this for the D5S:
Your settings should look like this for the D5S MINI: