Here's the usual with Windows 7
https://www.howtogeek.com/96805/how-to-reset-your-windows-password-without-an-install-cd/
And for Windows 10
https://www.howtogeek.com/222262/how-to-reset-your-forgotten-password-in-windows-10/
If you are going to clean it, just do a full factory reset. This varies with each PC so check with the maker how to do that.
My husband died Jan 15, 2015. I have been trying to clean his computer to sell it. I can't get past the password for the main sign in for Windows 10. Couls someone please help? TIA

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