@hwolfehall Not sure there is an API for those actions but here is simple instruction how to delete/reissue a certificate. 
You can do them in batch as well which makes it bit more quicker.

Hopefully this helps!

Viewing issued certificates

If you're logged into your platform as the Superadmin, you can see all of the issued certificates associated with a course or a learning plan. To do so, access the Admin menu, then choose the Certificate Template option from the Settings section. On the main certificates page, find the certificate you want to view, then press the issued certificates icon.

The system will display a pop-up window, where you can use the dropdown menu to view the issued certificates for a selected course or a learning plan. Now, you will see the list of all users enrolled in this course or learning plan. Select the users of interest, then, from the On Selected dropdown menu, choose whether to issue certificates to the selected users or delete the issued certificates for the selected users. The action will be applied as soon as you choose an option.

Please Note! If you make any changes to a certificate template, these changes will not affect the certificates a user previously earned before the change was made, until you delete and then issue the certificate again for that user.

Once a learner receives a certificate upon completing a course or a learning plan, the certificate will be associated with the user and available for download. When a certificate template is deleted, it will no longer be available for download, not even by Superadmins.

Thanks all.  I know how to do it manually on the front end.  It is just that I have more than 1000 records across about 100 courses. 

@Olli-Pekka Haataja you mentioned batching this.  Can you explain?  The only way I can see to do this is to go to each certificate, select the course, manually tick off the users to delete (and NO WAY to SORT the list to match alpha or other stare and compare list), select Delete.  Am I missing a bulk action?  

Thanks!   

@hwolfehall by batching I meant exactly what you meant that do by each certificate, select each course and the tick off the users. But when we are talking 100 courses and 1000 records, thats not any way easy task so batching quite does not feel agile there so no you are not missing a bulk action.

Unfortunately, I don’t know how to do this quick and easy.