You should be able to go into selection mode (the picture of the hand) to select the element you want to remove. If you end up selecting a button but want to select its container (table), you can use the up button on your keyboard and wait until the green outline shows what you would like to remove. Then you can hit "delete" to remove it.
If that doesn't work for you, you can go into source mode (double-click on the component) and select element inside the tab in the tree on the left that you would like to remove and hit "delete".
#DashBoard