After Destroying WebLogic JRF Based Stack - ADF DB Repositories Still Exist?

Summary

After Destroying WebLogic JRF Based Stack - ADF DB Repositories Still Exist?

Content

Hi there,

I just follow this tutorial and had setup a JRF WebLogic stack successfully.
https://oracle.github.io/cloudtestdrive/AppDev/wls/ll-jrf/?lab=optional-lab-steps

At the end I follow destroying the stack which is created by choosing from Marketplace. All the stacks are deleted successfully except database schemas/users such as OPSS, MDS... etc. which are created automatically with terraform creation job.

Is this a bug or am I missing sth? I was expecting the destroy operation also should have destroy database users, too? 

Please find below screen captures for the case.