Currently, 'dsync diff' will show (conflict) files including any that does not exist on either side (local or remote) and requires user to those cases manually. If you rm a file locally and push, Drive keeps it, and the next pull brings it back. To remove something, delete it on both sides yourself (locally plus on the Google Drive).
But this is a fair ask, I'd keep the default behaviour of 'no delete' but I'll work on to add a --delete flag for users to override that (in the release v0.4.0 this week). Thanks for the feedback.