Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I want to uninstall office 2013. I want to install 2021 so I can have publisher.
You should be able to uninstall Office 2013 from Windows Settings (or Control Panel, if you have an older version of Windows).
You can only install Office 2021, with Publisher, if you have a license for Office Professional 2021.