Delete BI Folder with permission set to Open

Summary:

Delete option Enabled even when permission is set to Open

Content (required):

With admin user we created the following folder structure

Shared Folders>Custom>Custom_1>DM_Reports>....

Now, if we change the permission in DM_Reports Folder for Bi Administrator Role to Open we are still able to Delete it.

if we go up in Custom_1 and put Bi Administrator Role to Open we are still able to delete Custom_1 but not the DM_Reports( the delete option is greyed out), however if I delete click on Delete button of Custom_1 the entire folder gets wiped out.

Any solutions/leads for this