Unexpected long delay to start review process and withdrawal of article We submitted an article to a SCI journal 2 months ago. Since day 1 the status of article is "Editor Assignment Pending". In the journal introduction they have mentioned that on average 1st review response takes 70 days.
As the start of review process usually takes 5-15 days in my area of research; therefore, we sent an email after 30 days and 2nd email after 45 days but there is no response from editor. In second email we requested to withdrawal of article so we may submit it to another journal. 
Can we submit the article to another journal before hearing the response from editor? 
Usually in my area of research the articles goes into review process within 5-15 days and it takes 2.5-4 months to get 1st review response.
Today it is very difficult to find reviewers, especially good and timely ones, unless the journal is very prestigious or rewards them highly (eg with editorials).

Having said that, this journal seems to be handled poorly. Thus, I would suggest you to pursue another scholarly venue.

If your email was clear in stating that you were definitely withdrawing the manuscript, then you can submit it wherever you want already.

Be prepared though that they may try to dissuade you stating that the revision process is already quite ahead (which could be true but not necessarily).