The following steps are intended for the LG Rumor.

Press the Menu/OK button.

Select Settings/Tools, then press OK.

Select Settings, then press OK.

Select More….

Select Security, then press OK.

Enter in the Lock Code.

(Note: The default lock code is the last 4 digits of the phone number.)

Select Erase/Reset, then press OK.

Select Reset Phone, then press OK.

Press the OK button to confirm.

Once the phone restarts, it will need to be set up for the first time.