Adding new "roles" in HANA system

Hello,

Is there way to drop old "roles"  from Security tab in HANA system and add a new One??

In my first project I had created my repository with new roles and shared the project. Later I had deleted the entire project and repository and create a new one. But still I can find there are few items are still available in repository and in content folder. I am able to delete those items. After creating a new project with new schema and user role, I was trying to assign the same, But I can able to locate old "roles". The one I have created newly, not showing at all.

Can you help me with resolve this issue?

Thanks

Avijit