From what I've been able to find out, the "anti-slavery clause" wasn't deleted by the drafting committee but later, after the Declaration had been presented by the committee to the Congress as a whole. Jefferson blamed the South Carolina and Georgia delegations and some of the "Northern brethren" who benefited from the slave trade.
One source (R.B. Bernstein) says that Adams fought the deletions, and the timid Jefferson didn't really express his reaction to the deletions. Another (Gary B. Nash) says that Adams particularly approved of the language in the anti-slavery clause. I don't find anyone saying that Adams killed or tried to kill the passage either in the committee or in the Congress.
It is likely that some of the objections from 'northern brethren' came from convention slave owners Carroll and Chase from Maryland, Franklin from Pennsylvania, Hancock from Massachusetts, and Jay from New York.
Don't be concerned about the clause deletion....it is a bunny path. Its importance lies with the fact that Jefferson paid more than pay lip service to cessation of the slave trade.
“I don't find anyone saying that Adams killed or tried to kill the passage either in the committee or in the Congress.”
The next year Adams, speaking out against a bill to emancipate slaves in Massachusetts, said that the issue was presently too divisive, and so the legislation should “sleep for a time.” (Henry Wiencek 2004).