You can delete front panel items from the block diagram, but you have to enable that option first.
Under the Tools menu, select Options, then use the pull down menu to select Block Diagram. Check the box "Delete front panel items from diagram", this will allow you to delete controls and indicators from the Block Diagram.
The option may not take effect until the next time you launch Labview, so you need to close LV and reopen it to see if it takes effect.