There are two things you can do to drastically reduce the size of files related to SQL Server on Virtual Machines (or your own computer).  
  1. After you back up a database, go into the backup folder and zip up the backup file and delete the original backup.  This will reduce the file size by up to 90%, and some of those files are huge.
  2. Sometimes the transaction log file size can get out of control.  Follow the steps outlined on this link to shrink them.

Also, when you create a SQL instance, consider whether you need full back up (generally the default setting). Setting the instance to a simple recovery model might be all you need and will save on resources.