Delete points on one side of a line in QGIS

I have a bunch of points and line that represents a boarderline as shown below:

I want to delete all the points one the right side of the line, and letting the points in the left side stay. I dont know how to do that without being a polygon with closed paths. I have tried to use spatial query, but its only working with polygons as far as I know. What can I do?