Unprotect Excel 2010 workbook - not a shared workbook

I know that thousand of answers addressed this issue, but none of the responses helped. My workbook is not shared.
Inadvertently I placed a double protection on the workbook of 73 tabs in it. It's not a problem opening it. First it is asking for a password showing the file name, and then there is a second request for password, saying that the workbook is reserved for my name and enter password for write access, or open read only.
However, I can't change the tab names, which is vital. What to do? I tried to un-protect, re-protect to no avail.
So how can I permanently remove the protection?
Thank you.