SSDT is a nice simple way to compare your local SQL database with your SQL Azure database. You can then execute the script it makes inside Visual Studio to update you Azure database.
Normally I would use database first but in this instance I had stored procedures to run and used database first. This meant could not use migrations to merge the schema changes.
Below are the visual steps.
In SQL Sever Object Explorer select the db and right click to expand and choose data comparison.
Choose the Azure DB and enter your credentials and select compare. This may take a minute but will show the differences in the databases.
The you can select update to run the scripts. But in my case I had to turn off “Block on possible data loss” as I was deleting tables knowingly.
Select update to run the scripts against your Azure database.