The first time you start iStudiez Pro, the app offers you to load Sample Data.
It is a set of courses, classes, instructors, etc. for you to get familiar with the app.
Do the following to delete Sample Data from iStudiez Pro:
Go to iStudiez Pro > Settings > Data Managing > Delete App Data.
On Mac you can delete Sample Data the following way:
Go to iStudiez Pro > "Data" menu > Delete App Data.
NOTE, it will delete ALL data you have in the app.