We had some databases that were 25 gb each due to some large media items.
To shrink the database, it is not as simple as deleting the large items.
After you have identified and deleted any unnecessary items from Sitecore, do this on each database (or publish the parent section) and then Empty the Sitecore recycle bin (in each database, via the Sitecore Desktop menu).
Then you have to run the Sitecore Clean Up Database wizard. This will remove the orphaned items from the DB. Finally you can shrink the databases and the space will actually be reclaimed.