You can scale-up or scale-down Azure SQL database using ALTER DATABASE statement:
ALTER DATABASE WWI MODIFY (SERVICE_OBJECTIVE = 'P6') -- or ALTER DATABASE CURRENT MODIFY (SERVICE_OBJECTIVE = 'P2')
If you try to change service level while changing service level of the current database is still in progress you wil get the following error:
Msg 40802, Level 16, State 1, Line 1 A service objective assignment on server '......' and database '.......' is already in progress. Please wait until the service objective assignment state for the database is marked as 'Completed'.
Re-run your ALTER DATABASE statement when transition period finishes.