Notezilla doesn't delete pictures when syncing, unless you are editing the Windows sticky note (with picture) in phone, the picture will not disappear on your desktop. Only if you edit the note on your phone, the note will get synced with the desktop and you would lose the picture. Otherwise, Notezilla would sync and keep the picture on your desktop. Just that you won't be able to view it on your phone.
Please note that currently Notezilla phone apps cannot show pictures.