"Replace" button in post selector should not unset the post

When a post is selected, there is a button in the sidebar to "Replace". Clicking this unsets the selected post, which is not what I expected that button to do. I expected it to re-open the modal and give me an opportunity to select a new post, or potentially, cancel (undo) my choice to select a new post and maintain the selection I had previously (this is a fairly important UX consideration!).

I propose that "Replace" does what I expected, maintain the state of the connected post but open the modal, where selecting a new post would replace the selection, and cancelling out of the modal would maintain the previous selection. Then add a second button to the sidebar to unset the post selection, because that functionality is _also_ needed. This button could be labeled "Remove" or "Reset" or "Unset" or "Unlink" or something along those lines.