You might be able to withdraw/retract the manuscript. This might be possible using the web interface by which you submitted the manuscript. Alternatively, you can write to the editor or associate editor that is processing the manuscript. Do not submit the manuscript to another journal until you have withdrawn/retracted the manuscript.
EDIT: The question has been edited since this answer was written. It is now apparent that the reason to withdraw/retract is to resubmit to a journal with a higher impact factor. This raises ethical questions.