What can i do to unlock my iPhone 6?

Locked how?

If you forgot the passcode on your iPhone, or your iPhone is disabled or unavailable -

If you forgot your iPhone passcode - Apple Support

If your phone is carrier locked - How to unlock your iPhone for use with a different carrier - Apple Support

How to unlock your iPhone for use with a different carrier - Apple Support

If your phone is Activation Locked - How to remove Activation Lock -

How to remove Activation Lock - Apple Support