The Amend action does not delete the original copy of the submission. However, evaluators on your project only have access to the amended version of the submission. Note that the original submission is always accessible by the project owner.
Here's what it looks like once a submission has been amended.
You are able remove Amended Submission which they will be removed from the project entirely. This can be done by going to Actions - > Delete in which after performing this action, you will not be able to see the Amended Submission.