Can a Ashkenazi do hatarat nedarim on kitnyot? According to Halachipedia the Rosh holds that one can do hatarat nedarim (annuling of a Neder) on a meritorious personal minhag. The pri chadash says that a minhag of your parents isn't binding upon you until you've observed it once. Therefore it sounds like it's considered a personal minhag since you're the one hiding it upon yourself. Additionally in America there aren't really any communal minhagim as we're basically a mishmash of everyone. Therefore aren't all ashkenazi minhagim (like kitnyot) now personal minhagim and subject to hatarat nedarim? Am I missing any information? Any one know any discussions about this?
Consider what the Shulchan Aruch writes in Y"d siman 214:2 (the fairly loose translation is my own):
קבלת הרבים חלה עליהם ועל זרעם; ואפילו בדברים שלא קבלו עליהם בני העיר בהסכמה, אלא שנוהגין כן מעצמם לעשות גדר וסייג לתורה; וכן הבאים מחוץ לעיר לדור שם, הרי הם כאנשי העיר וחייבים לעשות כתקנתן, ואף בדברים שהיו אסורים בהם בעירם מפני מנהגם ואין מנהג העיר שבאו לדור בה לאסור, הותרו בהם אם אין דעתם לחזור.
Something that a large group of people have accepted upon themselves applies to them and to their children, even things which were not unanimously agreed upon rather that the group began practicing on their own in order to make a fence for the Torah. And those who come from outside the city to live there, they are like the people of the city and are obligated to act in accordance with their practice. And even things which were prohibited in their own cities but the practice in the city to which they have come is to permit the practice, it is permitted to them so long as their intention is not to go back to their city of origin.
The Shach there (ס"ק ז) qualifies this by saying that it's only true if the minhag was established by a talmid chacham, and, as stated by the Kuntres Tov Ayin of the Chida (brought in the Sha'arei Teshuva in siman 453 ס"ק א) this minhag was established by "קצת גדולי ישראל" (see the whole Sha'arei Teshuva, he has a bit of an arichus on the chomer haminhag).
The same idea can be found in Pesachim 50b where we see that a minhag accepted by certain merchants not to travel on erev Shabbos between two specific places prohibited even their children from doing so even though the reason did not apply to the children. It certainly seems like there is no heter of such a minhag.
Perhaps one could have a leg to stand on with the Tur (O"C 453) who says that not eating kitniyos is a chumrah yeseirah and not the minhag, or with Rabeinu Yerucham brought by the Beis Yosef there (Toldos Adam V'Chava nesiv 5 chelek 3 41a) who says that it's a minhag shtus. However, the Rama already says that the minhag in Ashkenaz is to be machmir "ואין לשנות".