In Klenty, you cannot delete/remove prospects from the cadence completely, once you have added them. But you will be able to stop the cadence for the prospects, which is equivalent to deleting/removing them from a cadence.
In order to stop cadence for the prospects, Open the cadence > Prospects > In Cadence > Filter(if needed) > Select All or just the required prospects > Stop Cadence
Once this is done, the prospects will move from the In Cadence subsection to the Stopped subsection within the Prospects section present within the cadence.