To delete a specific node, select the node on your canvas. In the panel on the right, in the top right corner, select the 'bin' icon. This will remove the node and all subsequent nodes that were connected to it from your flow.
Once you've selected a flow, a number appears in brackets next to the 'bin' icon at the bottom of your list of flows. This indicates the number of nodes that were deleted from this flow. Clicking on the bin icon brings up a panel that displays all the parent nodes that were deleted from the selected flow as well as the children nodes connected to them.
To restore a deleted node to the canvas, simply drag and drop the node from the recycle bin onto a "node placeholder" in the canvas. The system will prompt the flow-builder whether they only want to restore the parent node, or if they want to restore the parent node as well as all the child nodes associated with it.