Please explain SQL Azure "master" database
Just a note: you will not be charged for the master DB.
master is a required system database that's responsible for holding info about all the the other database on the server instance, system metrics/config, managing logins & database creation etc, its read-only and can't be removed.
You will need to create a new database and deploy to that.
The master database records all the system-level information for a SQL Server system. This includes instance-wide metadata such as logon accounts, endpoints, linked servers, and system configuration settings