Deleting note types safely


I want to clean up the long list of note types available in my Anki. It is indicated that for some of them I don’t have a single note, meaning it should be safe to delete them. Yes, I am asked for a full sync.
Is it still safe to delete them?

Many thanks for you help!

P.S.: While am at it: I have experiences that on some notes the answer and question are suddenly switches, and I have made sure to not use a note type that does that. I just have to choose some other note type and it works fine again.
Do you think I have mixed up my note types or is there a know issue?

P.P.S.: Sorry for the inaccurate vocab, I’m not that deep in Anki (yet)!

If you use Anki on other devices and sync your data using AnkiWeb, you should make sure all devices are in sync before doing a full sync to avoid losing data. See Syncing with AnkiWeb - Anki Manual

You have to check your card templates to know the exact issue, but maybe you accidentally clicked the Flip button in the card layout screen (accessible from the Cards button in the editor)?