How to Perform a Factory Reset on Samsung Replenish

First, try this:

From the main home screen, tap menu
Tap Settings, then Privacy
Tap Factory data reset
Tap Reset phone
Enter your password if required, then tap Erase everything to confirm
If that doesn't work, or if your phone is frozen:

Turn the power off. If your Samsung Replenish is frozen, pull the battery out and reinsert it
Hold the Volume Down button, Call and End until "Samsung" appears on the screen along with a menu
Select Master reset device
When the phone is done erasing, choose the option to reboot