For our journal we use the DOI plugin to generate the DOI numbers. We were succesfully able to get it working and registered the latest articles with mEdra.
However, we don’t want to register DOIs for all older articles with mEdra. But on the front end of the journal website, the DOIs for older articles are still shown (and lead to not found pages if visitors follow the link).
You will find the clear and exclude options on the metadata form of each object type (e.g. articles, galley, supp files) you have configured to assign the DOIs to. For example for articles, as editor you will find these options when you edit an article metadata form ( Editor > Submissions > articleID > Summary > Edit Metadata):
Select this checkbox to clear the existing DOI for this article.
Exclude this article from assigning it a DOI.
Also, on the issue data page you will have the options to clear and exclude all objects of that issue: