if I reset my passcode by the Method provided, is it erasing my data?

If you forgot your passcode, the only way to use your iPhone again is erase and restore it. Your data will be erased.

If your iPhone is displaying "iPhone is disabled connect to iTunes" then your data has already been erased. The only possible way to avoid erasing your data is to enter the correct passcode before that happens.

If your phone is disabled, your data is already gone.