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

Administrative Note:

Welcome to the forum.

Sorry, but your post does not comply with Rule #6 of our Forum RULES:

Don't post questions regarding breaking or bypassing any security measure.

Such threads will be closed and repeat offenders will be banned. This includes posting of links to sites that offer software, code or services to do this or the posting of code to remove passwords.

Thread closed.