Downgrading SQL Server database and moving it to another computer
There's no such thing as downgradning the physical database. You would have to (use a tool that) script out your objects (CREATE commands) and the data (as INSERTs or some BCP files). And hope that you don't use anything on your 2019 that isn't available on 2014.

Such tools can be BACPAC, SSDT, "Generate Scripts" in SSMS.