Do factory reset delete everything off Android Samsung galaxy?

A factory reset on your Samsung Galaxy is designed to erase all user data and restore the device to its original system state. This process removes apps, settings, and personal data stored on the device's internal storage. However, while a factory reset is effective for most users, it may not completely erase all data to the level required for highly sensitive information. 

What factory reset does? Removes all user-installed apps. Deletes personal data such as contacts, messages, photos, and videos. Resets system settings to default.

What factory reset not do?  Some data remnants might remain in unused storage areas. If the device wasn't encrypted prior to the reset, data recovery might be possible using specialized tools.

How to permanently delete everything off Android (Samsung Galaxy):

Step 1: Before proceeding, ensure you've backed up any data you want to keep. You can use Samsung Cloud, Google Drive, or other backup solutions.

Step 2: Encrypting your device ensures that any residual data is unreadable without the encryption key.

Step 3: Go to Settings > Accounts and backup > Manage accounts. Select your Google account and tap Remove account. In the same Manage accounts section, select your Samsung account and remove it.

Step 4: Go to Settings > General management > Reset > Factory data reset.

Step 5: Scroll down and tap Reset. Confirm by tapping Delete all or Erase everything.

Step 6: The device will restart and begin the reset process. This may take several minutes.

Step 7: Erase the whole device with a dedicated Android data erasing app.

In short, factory reset won't delete everything off Android Samsung galaxy phone. The data is still recoverable. You have to take additional means to permanently erase data from Android phone.