We would like to limit the ability for customers and agents to delete an issue. Currently we have the following implemented for Delete Issues on the Permission scheme (fig.1).

So basically we only want Administrators to be able to delete an issue. We can delete/remove the Service Desk Team. But there are still two other options that have permission to delete issues.
My question is what the other two options represent?
1. Project Role -> atlassian-addons-project-access
For what does this project role give permission to? Is it if you have any add-on for Jira, you can still delete an issue when you are working in the addon? Or does it also give permission to delete an issue if you have agents that connect to Jira with another application, such as Top Desk for example?
2. Service Project Customer - Portal Access.
Does this option gives the permission to delete an issue to customers in the portal?
If not, what does it mean?