You can uninstall PokerTracker 4 and PostgreSQL (the program where PokerTracker 4 stores your poker data) via the Windows Start menu, Settings menu or Control Panel menu:
Guide: Uninstall or remove apps and programs in Windows 10Once PostgreSQL is uninstalled the data directory is left behind so if you are sure you do not need the data again you can delete it:
C:\Program Files\PostgreSQL\x.y\data\
where x.y is your PostgreSQL version although you may have it installed in another location.