1. Disconnect the integration.The ability to disconnect a Marketing Cloud account from the Sales or Service Cloud account is only available for Enterprise 2.0, Core, and Lock & Publish accounts with version 5.493+ of the package. The account must utilize connected app authentication.
2. Refresh the sandbox.Sandbox refreshes complete in hours, days, or even more than a week, depending upon the number of customizations, data size, number of objects, configuration choices, and server load. Also, sandbox refreshes are queued, so there could be a delay after your request.
3. Reconnect the accounts.This process connects your Marketing Cloud account to the corresponding Sales or Service Cloud org.
4. Complete Connected App authentication setup.Complete these steps to finalize the connected app authentication setup, which manages all cross-cloud authentication from the Marketing Cloud into the Sales and Service Clouds.
5. Synchronize data sources.If you use synchronized data sources, all synched objects and data are deleted after disconnecting the integration and must be recreated.