How to remove automatically inserted rest to insert notes?

I made some mistakes so I deleted a note in the middle. A quaver rest is automatically added. I need to insert a quaver between the third and fourth notes, but I cannot, probably because the quaver rest is filling the bar (if it is the correct term). I think I need to remove the rest to insert a note, but how? I cannot delete it, and I cannot it to the fourth position so that I could replace it with a quaver note.

Other than deleting everything after the third note and do it all over, is there a way to just insert a note after the third note and remove the automatically-inserted rest?