To unlock the phone with Octoplus, you will need the hardware box that attaches to the phone. This is expensive and not reliable, if you plan to use it only once. However, there are 3 methods to reset your phone (the only thing you can do when the phone is locked with a pattern lock), but only one will work. The other two require access to the phone's dialer and settings menu.
To factory reset the phone, turn it off, then press Volume Down + Power button + G Key until you see the LG logo. The phone will begin the procedure and reset it to the factory defaults.