To move a planned inspection from one inspector to another you first need to open the other inspectors desktop.
Do this by clicking on the dropdown part of the Desktop button and choose view anothers desktop.
Then select the contact's diary from the list.
Now you can see the selected contacts diary.
Select the planned inspection that you wish to change and select another inspector in the Assigned To dropdown list. Press save and close. The inspection will now move to the selected contacts desktop.