One of the coauthors withdraws their authorship after submitting a paper Is there a problem to change (reduce) list of authors of a paper after it has been submitted to a journal? I am one of the (ten) co-authors of this paper. After the review and changes we made in the paper, one of the coauthors withdrew as a co-author of this paper. 

Is this OK? What is the procedure in such cases?
It’s definitely weird, and a clear indication that something is going on with a paper. Basically, I can see two cases were this could happen, and both are not exactly great signs for the quality of a submission:


The removed author was just a “courtesy author” without any real impact on the work. (S)he wanted to tag along at first, but now when people started to nag her/him to do real work, (s)he is rather out. In this case, it is ethically entirely okay to proceed without the additional author, but one wonders why the courtesy author was on the paper in the first place. While this does not say something about the quality of the paper per se, it leaves a certain sour taste in the mouth with regards to the ethics of the rest of the authors.
The removed author was a “real” author in the sense that (s)he actually contributed to the work, but now feels that the submission is either so bad that (s)he does not want to be associated with it, or that the results are in fact wrong or unethically generated (e.g., because the co-author assumes that all or part of the work of somebody else was fabricated or is otherwise inaccurate). I think I do not have to explain why this would be a very bad sign for the quality of a submission.


What I would suggest in terms of procedure is full disclosure. Don’t just silently remove the author — in this case, the thoughts of the editor are very likely to wander to the two cases above, and this will make him look very carefully at your submission. Explain exactly what happened, and make sure to explain how it has nothing to  do with the quality of the submission. If you can’t do that (e.g., because the co-author actually withdrew because (s)he thinks your results are wrong), it is simply better for everybody to withdraw.