Is there anyway to downgrade to iOS 6 on iPhone 4?

I want to downgrade on iPhone 4 is there anyway to do it if so please give me a link

Have you jaikbreaked the device and have access to system root?
You will need the custon firmware. For your device for ios6 than you will need the custom rom. For ios6, and offcourse a custom recovery must be installed on the system
that will do the upgrade for custom rom.
You have to flash the custom firmware carefully on the PC through any utility.
That is the most dangerous step, where if system partition are not created well it will hard brick the device.
and leave the system blank, what no recovery may cope out.
Once you did it, rest of the things are simple flashing the custom rom through custom recovery installed.
If you are not going to use any custom rom than there's no use to install a custom recovery.
It is useless to take risk in downgrading.