In the following example, we remove all subscribers who have not opened a mailing in the last 365 days:
First, create a new target group under Subscribers > Target Groups based on opening behavior, and select "Opened within a specific period of time". Set the operator to "Not opened" and specify a period, e.g., 365 days.
Using profile enhancement (Subscribers > Profile enhancement), you can remove all subscribers in this target group from a specific subscriber list.
Select the subscriber list, the target group you just created, and the "Change list assignment" option. Then specify the subscriber list from which subscribers should be removed and select "Remove subscriber".
If a subscriber is no longer assigned to any list after removal, they will be removed from your account.