From your 'My Hub' page (please see below)
On the left hand side of your account, you will see the side menu in which you can select 'Contacts'.
Click the client profile followed by 'Assignments' from the list below the client profile picture and select 'Programs'
You can then simply click the program you are wanting to change
And in the top-right, if you click the pencil icon you can make the necessary changes.