In the UV Editor window,
 If you enable the "*Keep UV and edit mode mesh selection in sync*" option [![enter image description here][1]][1], then the vertices you select in the UV editor will also be selected in the 3D edit window.

You can then go to the **3D window** and delete them.
Don't forget to disable the "*Keep UV and edit mode mesh selection in sync*" option afterwards.
 
[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/1Sfq0.png
  [2]: https://i.sstatic.net/7p0Ia.gif