How to reduce the volume of the working Microsoft SQL database?

Question

Windows Server

How to reduce the volume of the working MSSQL database?
There is a windows server 2008r2 with MSSQL (2014) installed, with a separate disk for the database.
Recently it was noticed that the base uses free space very quickly, the algorithm for filling the base may have changed (with a new release of the application that uses the base).
Is it possible to somehow compress (not delete) the space occupied by the base? There is very little space left, there is no possibility of expansion yet.
I found several articles, but they advise different things.
https://msdn.microsoft.com/en-us/library/ms189035.aspx
straightpathsql.com/archives/2009/01/dont-touch-th...
I would be glad for any information, especially detailed about the consequences or verified.