The following techtip describes that a 4D database can be opened without any of its design windows appearing by simply holding down the option or alt key while the database is opening.
https://kb.4d.com/assetid=75991

However, if you close the database and re-open it again, the windows will re-appear.
To prevent the design windows from opening subsequent times, after opening the database with no windows showing, open the explorer. The next time the database is opened, only the explorer window will be shown.