Its a common misconception with clients just getting started or used to using the wizards that if they flag records by accident that they need to restart from the beginning and they're permanently deleted.
This is untrue, when you flag records, what happens is they're only 'Logically' Deleted, meaning they're ignored from future processing, but they're not permanently gone just yet.
So if I were to take a look at a DBF where I flagged records, we can still see them.
In below screenshot I ran our example1 file through the default single file wizard process and flagged the records at the end when I meant to raise my mimimum for flagged to 96 instead of leave it at 80. after I'm out of the wizards, I can click the file name and then click 'Show Flagged records'
We now see the data in the dbf, but we see the records with the little black boxes on the left hand side, those are the 'Flagged' records
If I want to 'UnFlag' them, then while in this view - there's a table menu up top that is hidden unless you're in this view.
Now from that menu - choose Recall Records...
Change the Scope to 'All' , then click 'Recall'
now you can continue on using this file outside of the wizards, going back to matching or restarting the matching without needing to re import the file, flagging at a higher score if you forgot to raise it before clicking flag, or adjusting your weight/constraints etc and rerunning if needed.