Can't remember my passcode
You should put your device into DFU Mode.
Here are the steps:

Plug your device into the computer

Press and hold both the power and home buttons until the screen goes black then release the power button still holding down the home button.

The screen should stay black and your device should popup in iTunes saying it needs to be restored.

Click restore and confirm any prompts that popup.

Let iTunes restore your device and do not unplug your device.

Once you're finished it should take you to setup and when activating enter your iCloud details when asked.