In order to understand about the revisions of the certificates within the Work Order, Please check out the below article:
https://qualer.freshdesk.com/support/solutions/articles/6000193696-report-revisions-and-visibility
You can create the revisions only after locking the certificate. To do that click on the arrow next to the certificate. See below:
Then click on "Lock Document" from the menu. See Below:
Then Click on "Generate a new revision" & This how you can generate revisions of the certificate. See below:
To delete the revisions you have to first unlock the the certificate then click "Delete" and this is how you can delete the revisions. See below:
Here is the video as well - https://storyxpress.co/video/koek0vkv9uuyka64i
Note : By default system will delete the latest revision. No matter how many revisions you have created also system will not prompt any information about the revision. It will just ask "Do you want to delete (Certificate name).pdf". So no need to worry that which one system will delete because it will be the most recent one bt default.