Update: I talked with my advisor about (1) the possibility of asking the editor about submitting our paper this journal X and (2) the possibility of me as the sole author to submit this paper. She said no and no :(
Background info: I am from the field of social science, and this paper is from my dissertation. My advisor provided funding for my dissertation ($9,000). My advisor has been very good to me. I just graduated last year and am now an assistant professor at another university.
I did plan to add my advisor as the second author of this paper, I also told her in an email I would like to submit this paper to X, the top journal of our field, and I attached the draft in this email.
Then I heard back from her yesterday with an edited version. In the comments, she told me not to submit to X because she is one of the associate editors which creates a conflict of interest--I emailed the editor to confirm and this is indeed the rule. This rule was not listed on the journal's website and my advisor did not tell me when I sent her the email saying I would like to submit to X journal.
I really want to submit to this X journal because I imagine it would help me a lot with my academic career. If I knew that any paper with associate editors as a co-author cannot be submitted to journal X, I would never send this paper to my advisor for comments.
I wonder if I can ask my advisor to withdraw her authorship and I will be the sole author for this paper so that I can submit to X. I am not sure how unethical my behavior can be? Or maintaining a good relationship with my advisor is more important than having a top journal publication? Any suggestions are appreciated!