I can't select or delete a bone and this blue circle keeps appearing? https://postimg.org/image/m00rul0vp/

When I left-click in edit mode, a black outlined-blue circle appears with a red line. What I'm actually trying to do is simply to select a bone, left-click the coloured arrows to move it and delete some bones. Now, I can't even select a bone in edit mode.
You have enabled Skeleton Sketching. You can disable it in the properties region N