Apple, Google and Microsoft decide what apps may run on their devices, so no app can delete their file apps for you. These are the strongest real ways to enforce it, from a personal checklist up to fully locked company devices.
Tick each step as you go — your progress is saved on this device.
Download on your iPhone, iPad or Mac, then open Settings → Profile Downloaded → Install. It switches off iCloud Drive, iCloud backup and photo syncing, and adds File-A-Cloud to your home screen. Blocking Google Drive, Dropbox and the Files app only takes effect on devices set up in managed ("supervised") mode. Remove it any time in Settings → General → VPN & Device Management.
This is the only way to fully enforce it. Upload these settings into the device-management tool you use, and it blocks other storage apps on every phone and computer you manage:
Whenever you share a file into File-A-Cloud from another app, the save screen reminds you to delete the original, so File-A-Cloud stays the only copy.