Good to know as I had started having all databases on my Mac synced with my iPhone. Now I have decided to manage my current tasks using one database with the information necessary and move the respective group to the area of responsibility DB on my Mac when the task is completed. At first I hesitated to delete all the other DBs on my iPhone, but now I can go ahead and save storage space on my iPhone as well as sync time.
I know this old but I found this after googling the same question. The warning that you get when you go to delete a database does make you think that you are deleting it everywhere: to make the mobile version more user friendly, can the message be changed to make it clear that it will only delete the database from this device. Thanks.