This is a common problem. The first thing you might want to inspect is the database size.
Navigate to C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\DATA
Check the size of SharePoint_Config database. If this database is taking more disk space you are at the right page.
Run the following commands and you should be good.
alter database sharepoint_config set recovery simple
alter database sharepoint_config set recovery full