I understand that you are facing an issue with phantom borders in Excel that cannot be deleted. This can be frustrating, but there are a few things you can try to resolve the issue.

1. Firstly, try selecting the entire worksheet by clicking on the box at the top left corner of the sheet (above row 1 and to the left of column A). Then, go to the "Home" tab in the ribbon and click on "Clear" in the "Editing" section. From the drop-down menu, select "Clear Formats". This should remove any formatting, including borders, from the selected cells.
   
2. If that doesn't work, you can try using the "Format Cells" option to remove the borders. Select the cells with the phantom borders, right-click and choose "Format Cells". In the "Format Cells" dialog box, go to the "Border" tab and select "None" for all border options. Click "OK" to apply the changes.
   
3. If the above methods don't work, it's possible that the borders are part of a table or a conditional formatting rule. To check for this, go to the "Home" tab and click on "Format as Table" in the "Styles" section. If the "Clear" option is available, click on it to remove any formatting, including borders. If the "Clear" option is grayed out, it means that the borders are part of a conditional formatting rule. To remove the rule, go to the "Home" tab, click on "Conditional Formatting" in the "Styles" section, and select "Clear Rules" "Clear Rules from Entire Sheet".

I hope these steps help you resolve the issue with phantom borders in Excel. Let me know if you need any further assistance!