Disabling API / Web Service access for ALL INSTANCES at once of PMadmin can be done via the PMAdmin site, following the guidance below:
Disabling API / Web Service access for A SINGLE INSTANCE of Password Manager can be done via the IIS Request Filtering, following the guidance below:
NOTE: The PMSelfService site REQUIRES access to files in the /PMSelfService/api/ container for normal functionality and this workaround is not compatible with the PMSelfService site.
If this workaround is implemented for the PMSelfService site, the PMSelfService site will not load correctly. Instead, it will only display a logo and a spinning icon.