Are there some services within your business that you only want Staff to be able to schedule clients for using the back office app? In other words, you want to create appointments for these services, but you don't want to allow clients to self-schedule them.
If so, the best solution is to create a Private Service which hides the service from being booked on the client facing scheduler by unchecking the "Show Service on Scheduler" checkbox.
To do this, go to Setup → Services and click into the Service you want to hide from being on the scheduler:
Once you are in the Service Profile screen, scroll down toward the bottom and find the "Show Service on Scheduler" checkbox:
Uncheck the check box and click the "Next" button at the bottom of the screen twice to get to the "Staff" tab where you can save and commit your changes.
After unchecking the check box, your service will no longer show up in your client facing scheduler, but will be available if you go to Setup a One Time Appointment through the back office and will display on all reports that you run in the application. A class can also be marked as private.