Over 1 million rows - how to delete blanks?

We have an Excel file that was exported from Smartsheet. Unfortunately when exported it brought over 1 millions rows - less than 300 rows have data. How do we delete all of the blank rows?

I know we could copy the data we need to a new spreadsheet, but we have already setup formulas, conditional formatting, etc. The file is kind of slow (shared via OneDrive) and we are working to reduce some of the conditional formatting, etc but I think the formulas checking a million rows has to be slowing it down some too.