Nurmi wanted to withdraw only because he had quit as a public defender and gone into private practice. The judge ruled he could not withdraw becaue of the case being so soon on the docket - there was no time for new counsel to be brought in. For a brief period though, Jodi wanted to represent herself and two other attorneys were assigned to assist her though she would be considered as lead counsel. I can't really recall how all this worked out with Nurmi back on the case, but it was not JA's doing to try to get rid of him, nor did he want to withdraw because she was a loser client - it all came down to money (private practice pays WAY better).
There's a post with a link about two or three threads back to I think it was someone's twitter page that listed all this and the dates each decision about it occurred and Nurmi's pay scale agreed upon, etc.
It would have been a riot to see her being her own attorney though.
