Hi Paul,
Thanks for the screenshots. You're actually not running into dependency issues removing the solution customizations - you're getting an error just trying to delete data. The error you are getting is a plugin error. You can disable the plugin in CRM by going to Settings > Customizations > Customize the System. In the default solution window that opens, click on "Sdk Message Processing Steps". Sort the steps by name, select all the ones that start with 'ClickDimensions' and then click the "Deactivate" button at the top of the list. Once the plugins are disabled, you should be able to delete the records you were trying to delete.
