In order to hard reset a Siemens SL45, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Siemens SL45 device will be brought back to the default configuration of a brand new device.
1. Press & hold the Power button until the phone turns on.
2. Enter your secret code, *#9999#.
3. Wait until the phone resets and restarts. Complete.