Not to difficult to fix. Add a new sheet and right click on "sheet1" and hit delete.
I have had corrupt files with things I could no longer select in Creo 2.0. I submitted it to customer support and they were going to look into it. I would highly recommend opening a support case and attaching your file. They really need to see that files -are- getting corrupted.
But! But!!!... now that the file -is- corrupt, do you really want to continue with it? Although you -can- delete the sheet with the phantom tables on it, you could just as easily get into trouble later on with even more issues. I'd suggest starting from scratch is your safest bet.
...And welcome to the forum!