What should a young man do if he fell in love with a girl he met online and wishes to marry her due to her commitment and readiness to fulfill his conditions, while his parents refuse his marriage to her because she is from another town, and he fears the consequences of having met her online and his parents' refusal?

You must repent from chatting with the girl online and over the phone, because it is a prelude to adultery (zina). If you are serious about marrying her, then perform Istikhara (prayer for guidance) and propose to her after obtaining your parents' consent, as obeying them is obligatory, especially given your feeling of discomfort towards her. The correct verse is: "Say, 'Shall We inform you of the greatest losers in [their] deeds? [They are] those whose effort is lost in worldly life, while they think that they are doing good in work.'"