Unable to delete vertices of Polygon Collider 2d in Ubuntu

In version 5.4 on Ubuntu I am able to create new vertices just by licking on the highlighted green line. But I can't delete vertices. I have tried holding shift, ctrl, alt, space, tab, x, d anything I can think of.

The only way i have been able to delete vertices is by using the property inspector and removing the array elements associate with them, but this makes it really hard to know which element corresponds to which vertice.

 

In version 2019.4, I can hold Ctrl then left click on the line (not the point) to delete them

 

Perfect, Thank you! The lines on either side of the vertex will highlight red when you hover over a vertex area holding control. When you left click, it will remove the vertex at the center of the red lines.

Thank you cdr9042.