I.R.I.S. Readiris 14 for Mac User Guide - Manual (Page 33)

Section 3: Basic Document Processing
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When you've gone through these steps, click Save to start the
text recognition and generate output documents.
Starting a new project
When you are done saving your scanned documents, or when you
want to start over:
 Click New on the top toolbar.
This command erases your documents from Readiris so you can
start a new project.