Unlock workbook/worksheet unknown password

I have an Excel document with several tabs, but it's all password-protected, the problem is the person that created this document, is no longer with us and I don't know the password. I've searched the forum and didn't find anything that could help me unprotect the workbook or the individual worksheets.
I did find instructions online and everything was fine until the last step, it would not let me change the file extension back to xlsx. (Found instructions here: link which breaks our rules deleted)
I'm not very techy, and have no idea how to work with codes, but I need to be able to use this document and make changes to it.
Any advice???

Thank you in advance for any help you can provide.


UPDATE: Nevermind, I figured it out.. yay