To move a task or entire workflow (i.e. connected tasks) into another experiment, you have to be in editing mode.
First, click on Edit experiment button up left of the canvas. Then click on the upper right corner of desired task and select the action from the drop-down menu. You can choose between Move task to another experiment or Move workflow to another experiment.
If you choose to move an individual task, the task is removed from the current workflow and the neighbouring tasks form a new connection.
If you choose to move the entire workflow, the workflow disappears from the canvas and is removed to the other selected experiment.