In order to remove the control lever you must first remove the cover at the front of the TOM unit. Once that is off you can get in there and remove the small pin that holds the lever shaft to the control mechanism. When you're going back together make sure the pin fits tightly. The pin in mine worked out once and rendered the hitch inoperable.
One little hint about the seal on the lever shaft. The one Deere will sell you is the original leather seal but I've had poor luck getting the system back together without damaging it. (There is also a dish-shaped metal retainer that you'll probably want to replace as well.) I replaced the leather seal with an appropriately sized o-ring and it hasn't leaked a drop since.