How to reclaim database space on Azure SQL Server after setting nvarchar values to null
Please defrag all indexes. As mentioned on this article, fragmentation can claim a lot space.

Run sp_helpfile to verify the log is not consuming space also. If the log is big run the following statement to recover space.  

DBCC SHRINKFILE (log, 0)


On this thread I provided some queries that may be useful about database size.

Hope this helps.