Can I turn off resume collection?
Yes! You can turn off resume collection (or re-label the field). Go to "Dropboards" and then click "Edit" on the Dropboard you want to modify.
Click the arrow to move to the "Application Form" section:
Under "Customize" look to the "Collect resume?" field option.
How about the cover letter / introduction?
This can also be optional or removed from the form altogether. Just below the resume option is a similar option for the cover letter.