Folder permission inheritance User

Hi,

Scenario:

outlook folder called "private" in.

User A gives read permission on this folder to user B.

The folder gets archived, User B can see the archived item of that folder of user A.

User A deletes the folder from outlook.

Few days later, he found out that user B can still see the "private" folder content on the vault.

he does not have that folder in the outlook anymore, it only exists under his vault,

how can we cancel the permissions on that vaulted folder?

thanks.