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.