In the "Navigator" it should be possible to delete a control by right-clicking into it and choosing Edit->Delete from the marking menu.
This is not possible when a different view has focus since in this case the menu entries are greyed out.

Steps to reproduce:
1) Open a Project of your choice.
2) Activate the "Properties" pane by clicking into a value field. For example: Width.
3) Right click onto a control in the "Navigator". Open the Edit sub-menu.
=> Delete, Cut and Copy is greyed out even so these Options should be available.

To perform a deletion on has to actively activate the Navigator by left-clicking into it.