accidental autosum huge document

So I have created the biggest "oops" in my life. I have a 45 page spreadsheet that i accidentally clicked one of the whole colums and clicked autosum. This has created a little bit more that 1 million rows. I have tried undo-ing, copying the content i need and deleting the column, and even trying to delete each row. Nothing has worked yet and I am desperately trying to find the answer to this question.

It is actually quite easy to recreate: open an excel spreedsheet, add a few numbers in the same column, click the header of the column to select the whole column, and then click autosum.

I would like to thank everyone in advance for helping me with this problem.