First, create a target group under Subscribers > Target Groups that is defined to only display subscribers who are on the retained address list. To do this, create a new target group in the target group overview using the "Create" button and give it a meaningful name. Then, under the "Definition" tab, select the condition "Retained Addresses" and then the operator "Email address belongs to retained addresses". This setting will search all your subscriber lists for addresses that are already on the retained subscriber list.

In the next step, open the profile enhancement module under Subscribers > Profile Enhancement and create a new profile enhancement. 

1. Subscriber Selection: Select the desired subscriber list from which the retained subscribers should be unsubscribed. If needed, you can also select all your subscriber lists here. Once you've selected the desired lists, add the target group you just created under "Target Groups". This way, the target group acts as a kind of filter for the selected lists.

2. Filter (optional): You can set up additional filters if needed. However, this option is optional and can be skipped.

3. Enhancement: From the "Modify" dropdown menu, select the "Subscriber list assignment " option and then select the desired subscriber list using the "Select subscriber list" button. It's recommended to choose the same subscriber lists that you already selected in the first step. As the second operator, select "Unsubscribe subscribers" from the dropdown menu. This will unsubscribe found addresses (retained addresses) from their respective subscriber lists.

4. Start: Review your settings once more and start the profile enhancement using the "Start" button. Additionally, you can automate the process under "Settings for time-controlled profile enhancement" so that the cleanup is automatically repeated, for example, every 14 days, ensuring your subscribers are regularly cleaned up.