Did you follow Microsoft's instruction for uninstalling Office 365? See Uninstall Office from a PC

Also try switching from MS account to Local account? See https://support.microsoft.com/en-gb/help/4027068/windows-10-switch-your-device-to-a-local-account

You can always switch back if it doesn't work. See Switch from a local account to a Microsoft account

I am no expert in Office 365 but these seem worth a try.