After I retract the deployment of the solutions in the SP2010 Central admin, I get some innocuous but annoying 'Missing server side dependencies" errors, which in turn give me errors when I do a database upgrade:
[MissingWebPart] WebPart class [6445560d-215d-3f59-3919-5c651b3e3f50] (class [ToolbarManager.Processor] from assembly [ToolbarManager, Version=18.104.22.168, Culture=neutral, PublicKeyToken=8e586c4c8b123d97]) is referenced  times in the database [Sharepoint_Foundation],
but is not installed on the current farm. Please install any feature/solution which contains this web part. One or more web parts are referenced in the database [Sharepoint_Foundation], but are not installed on the current farm. Please install any feature
or solution which contains these web parts.
How can I do a clean uninstall?