Hai Scott Bellows,

To remove the respective item from your invoice, go to Settings search for Developer Tools you will find a button "Activate the developer mode". Once you activate the developer mode go to Settings > Technical > User Interface > Views and search for report_invoice_document and select the record with "Inherited View" field empty(because it will be parent view). Here you can find the code for the invoice report under "Architecture", then search for the line which which you need to remove( the code with keyword "on this account" or similar). Now you have to comment the code you found as shown in below image.

If you couldn't find the code in here. Go to "Inherited View" tab and click on each record you will see the inherited views of the invoice report. Here also follow the same steps, search for code and if found comment it.

Once you find and commented the code you will be able to print new invoices without the line. But remember this will be applied only for new invoices. 

and Please be careful while editing the code because it may affect your invoice report.