who wrote the documentation on this ? http://manual.audacityteam.org/o/man/time_tracks.html
why would you not write how to remove a point ?
…
after a month I found out you have to drag them outside the area …
I wrote it, and others reviewed it. 
But you did not read it all, because the information is there in the “Tutorial” section:
http://manual.audacityteam.org/o/man/time_tracks.html#warp
Drag points off the track to delete them.
In our development version, I’ve moved that information up into the “General method of use” at the top, and added a note about Undo.
So that change will be in the 2.0.5 Manual.
Gale