There are several levels of "rejection" here.
First, if you mean outright removal from the canon, as in The Jefferson Bible, no large denominational body has done so that I am aware of.
Secondly, since Paul wrote half the New Testament, he is the source of many of our doctrinal writings about items from the nature of salvation to sexual ethics. On matters of salvation, for example, there are those who argue for a distinction between the "original" religion of Christianity and that which came about after Paul ruined it. The former being a nice religion about peace & justice, the latter being an exclusivist religion about avoiding hell in the afterlife. An example is the "Christianity Before Paul" views of James Tabor. I don't know of any denomination who has fully embraced this view, although there surely are large numbers of pastors who would do so.
As far as sexual ethics go, Paul's writing in Romans 1 has been cited as the most authoritative biblical passage condemning (modern) homosexual practice. Thus, much of the discussion in modern denominations has revolved around the applicability, authority, or even sinfulness of Paul's writings on the topic. One such place such debate over Paul's writings could be seen was in the debates that the Evangelical Lutheran Church in America had over allowing non-celibate homosexual persons to serve as pastors leading up to a 2009 vote at its churchwide assembly. Neverthelss, I have seen that even among those who explicitly reject Paul's view on sexuality, nearly all still find his writings on other topics, such as communion, to be authoritative.
Examples of rejecting Paul's writings in the ELCA's sexuality debate:
1) Presiding Bishop Hanson was quoted as saying that "we won't let six verses" determine our policy on anything.
2) One of the policy documents from the ELCA charged that "Paul's pre-suppositions are irrelevant."
3) At the plenary debate during the 2009 Churchwide Assembly, one speaker got up and told a story of one of his professors in seminary. It went like this:
"The professor took a large bible and threw it as hard as he could against the wall. Its bindings broke and pages went everywhere. The professor said, 'This is how I feel about the bible." Then the professor lovingly picked up the pieces, cradled them in his arms like a baby, and said, 'This is how I feel about the Word of God.'"
Making a big deal about the distinction between "the Word of God" and bible passages you want to throw against the wall is one way of downplaying the writings of Paul (Romans 1).