How can 'last-saved' values be easily cleared in Collect?

1. What is the issue? Please be detailed.
I've uncovered a nasty little issue in my form that prevents it from loading in certain cases (I used last-saved for a field in a repeat, this causes a 'duplicate / try using indexed-repeat' error if the previously saved item populated this field with >1 repeat elements...), and I think I have users with existing drafts that will be affected and can't trash & redo these submissions with an updated definition.

I was hoping there was simple process I could get them to follow to clear the last-saved values if they do hit this error.

3. What have you tried to fix the issue?
I tried resetting 'Form load cache (.cache folder)' in project management settings, but this didn't work.

From the issue - it seems deleting last-saved.xml might do it - I located the file in the most recent definition folder and renamed it, this did clear the values in the next submission, but this is not an easy process for the users.