Your company Contoso has merged with TechOne and the organization name is changing to Contoso-One. You want the change to be reflected on the local OneDrive sync folder in Windows Explorer from Contoso to Contoso-One.
First Unlink your OneDrive account by Right clicking on the OneDrive cloud icon in the system tray, and choose Settings:
NOTE: If you unlink OneDrive and have SharePoint sites synced, you will need to resync them.
Select the Account tab:
Choose ‘Unlink this PC’:
You will receive a dialog to confirm the Unlink:
Once you have unlinked your OneDrive account, go to the O365 Portal as a global administrator: