I've tried to test the the data registry and data deletion functionalities, but it doesn't seem to work.

• First, I've created a test course, and invited some test accounts as participants. I've also created a forum and a assignment inside this course.
  
• Then I used these user accounts to create some forum posts and uploaded some submissions. 
  
• As course start and end date I've set dates in the past (over a year ago). 
  
• Under "Data registry" I've created a purpose called "Test"" and set the retention period to 2 days.
  
• I've then selected my test course, and set this  "Test" purpose as the purpose of my course. 

I've expected to find this course using the "data deletion" site but unfortunately it wasn't the case (also I tried it again 24 h later, and even some days later). Then I've tried to assign this purpose to the parent category of the course and then to the blocks and assignments but it wasn't successful. 

I wonder if there is a step-by-step tutorial? 

I first thought that these data deletion settings were very self explanatory, so I wonder why it doesn't work and what I did wrong.