How to remove features from geojson by mouse selection?

Question

There are these unnecessary lines in my geojson:

You see, not all the borderline was deleted when I merged two countries.

Is there any way to quickly select and remove the features in a practical manner, because there's more than one case like this I'm dealing with.

Thanks in advance.

EDIT: Deleted some of them by using Edit>"Remove Ring".

But there are still some which cannot be removed by this tool. Is there such plugin available, that will remove lines that are irrelevant with the polygon?

Answer 1

The problem of GeoJSON and shapefiles is that they have no topology (the limit between 2 polygons is duplicate, digitized two times, see Understanding Topology and Shapefiles)

But there are other solutions than removing features by mouse:

1) you can use a GeoJSON format that encodes topology

see TopoJSON

2) If you use QGIS

The result is not correct with GeoJSON (or shapefiles)

But you only need a topological GIS where the common border exists once and is shared between the two areas as GRASS GIS. And GRASS GIS is integrated in the "Processing/Sextante" menu and you can use v.dissolve The process is (in a transparent manner):

1. the layer is imported and cleaned (topology) in GRASS GIS
2. the command v.dissolve is applied
3. the resulting layer is exported to QGIS

Answer 2

Removed the others with the "Node Tool". Clicking a node to make nodes editable (nodes get surrounded by square boxes), then making a rectangular selection and pressing Delete does the trick.

It still has some bugs, though. Sometimes a group of connected nodes have to be deleted at a specific order, because they cannot be deleted all at once. (QGIS Dufour 2.0.0)