Underwood is the only one of the four who was listed on the preseason depth chart's two-deep, with an "OR" designation at starting nose tackle. The senior contributed in each of his first three seasons at UNC, appearing in 31 games and posting 35 tackles. He was limited by an ankle injury in 2013.
Webb was UNC's top-rated signee in its 2013 recruiting class, ranked as the No. 10 defensive tackle in the nation by Scout.com. The Erial, N.J. native redshirted the 2013 season.
Patterson, a sophomore from Roanoke Rapids, N.C., had practiced on both sides of the line since his arrival in Chapel Hill. He played defensive tackle last fall before shifting back to offensive guard in the spring due to depth concerns.
Heaven, a sophomore from Palmetto, Fla., redshirted the 2012 season and moved to linebacker for 2013, appearing in five games on special teams. He has transferred to Northern Iowa, according to a team source.
Another player, senior ram Brandon Ellerbe, has not been reinstated and will not report for training camp on Thursday. The Wadesboro, N.C. native was not enrolled for the spring semester, but had the potential to return to the team for the 2014 season.
Ellerbe played in all 13 games in 2013, totaling 28 tackles, 1.5 sacks and a blocked PAT. His best performance (5 tkl, 1.5 sack) came in the 39-17 Belk Bowl win over Cincinnati in December.
A sixth player, senior wide receiver Mark McNeill, has decided not to play football this season. McNeill, who is also a member of UNC's lacrosse team, appeared in all 13 football games in 2013, catching six passes for 107 yards. He played with the lacrosse program for the spring 2014 season and was selected in the Major League Lacrosse draft.
Senior linebacker Darius Lipford, who was listed as the starter at middle linebacker coming out of spring practice, entered the 2014 NFL Supplement Draft in July, but went undrafted.
All told, 15 scholarship players with eligibility remaining will not return for the 2014 season.