Delete 

Menu: Mesh->Edit mesh→Delete

To delete elements or nodes, select them in the usual way (see Entity selection), and then press escape (see Escape) to perform the action.

If the 'Also lower entities' check option is set then are deleted the selected entities and also its dependencies if possible (if are not shared by undeleted entities)

Note: It is possible to filter the selection, e.g. to select only triangles but not quadrilaterals (see Selection window (only Preprocessing)).

Note: Only lonely nodes (nodes of the mesh that do not belong to any element) can be deleted.