A reminder, if the above message is encountered when installing a windows service after removing a previous version, then
- Close all instances of Event Log viewer
- Close all instances of Services MMC (Microsoft Management Console) for all users on server
- Use task manager to ensure the old service process is not running
- Sign other users out of server if above fails
Since understanding the above the message no longer haunts me.
Stackoverflow post: How to solve “The specified service has been marked for deletion” error