How do you delete/amend a check-in document with an old version of the Questionnaire?

Summary:

After making updates to an existing Questionnaire, new check-in documents show the changes; however, any previously completed check-in documents do not. Is there a way to 'mass delete' previous check-in documents?

Content (required):

We currently have a Questionnaire in Production available under Me > Career and Performance > Performance. We need to made 2 of the existing questions required. I used 'Create a New Version of the Questionnaire' to accomplish this and now any new Check-Ins have the fields required as expected. We have multiple employees who complete the old version where the fields were not required. Any previously completed/in progress check ins do not update with the changes I made. Has anyone come across this? Is there a way to 'mass delete' in progress check-ins?