i forgot my 6 digit passcode and im trying to factory reset it my iphone 6

You must follow the directions in the Related Article Link at the top of this page, which is the link which brought you here. There is no alternative.

See this Apple support link→If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

Or watch this companion video ⬇️

But it did not work.

Then schedule an appointment at your Apple Store Genius Bar or Apple Authorized Service Provider for help.

How much it will cost me?

Nothing.

need to reset passcode on my iphone

Look at the post just above your post and follow the directions.

It works but maybe not at the first time, I did like 10 times and the last one worked out! Try it out!

Good luck!