Hi Heather - it's difficult for me to be sure without seeing what you're doing but I think the problem you're having is because the Delete Section feature works by selecting a range of points and there isn't a point at the exact location you want to select. The best thing to do is zoom right in to the location and use the Drag Mode (switch at top of map) to drag the points so that they are in the exact locations you want. Then you should be able to select the exact section you want to delete. Alternatively you could delete the section first and adjust it using the Drag Mode afterwards.
Trying to delete part of a route, but when I click on an arrow it selects an arrow either above or below what I've selected.