change back to factory settings samsung j7

Turn phone off.

Hold volume up + power + home and when Samsung logo appears stop holding power button.

Then wait for the Android recovery menu to show up. Once it does release the rest of the buttons still held down.

Use vol up and down to navigate menu. Power button to select an item.

Go-to wipe data factory reset do that then reboot phone from recovery menu.

Note that in some cases you may have to login Google account that was linked to the phone to setup the phone.