Database’s size can be optimized using Shrink command. It helps to release unused space. There’re 2 ways to do it: via GUI or via T-SQL.
- Connect to SSMS
- Select target database
- Right click > Tasks > Shrink > Files (or Database)
Sometimes SSMS estimates that there’s only few avaible free space (less than 1%) and the shrink is not interesting. However, it might be a doubtful estimation. I’ve gained more than 500 Mb instead of 1 Mb. So just take a try.