how?

https://musescore.org/en/handbook/barlines ?

In order for us to understand and assist better, it would help if you attached your score and described what you are trying to do in more detail. As it is, I can't tell what "line that separate notes" you want to move, or where you want to move it, or whether you want that movement to just be a manual adjustment to its position on the page of whether you wish it to have some musical meaning. All of these are relevant to any answer.