Do NOT remove the aluminum plenum from the carbs and then attempt to remove them from the engine separately. Doing so will break the fragile plastic tubes between the carbs. Keep the carbs attached to the plenum until you have them sitting on your workbench.
While you don't *have* to remove the tank, doing so makes it easier to deal with the airbox. The airbox top is a tight fit, and the gasket can stick and/or snag. It's thin and fragile and would be easy to break, so watch it.
On the front connectors, loosen the bands on the carb side only. Loosen both bands on the rear connectors. The rubber connectors may have hardened and they may be reluctant to let go of the carbs. The trick is to work on only one pair at a time. Work the carbs out of the rear connectors first. If you can't get them out with hand pressure, you can use a long screwdriver or equivalent between the cylinder head and the back of the carb assembly to exert gentle firm pressure forward. (One list member reports that a piece of 1" x 3" hard wood like birch works well.)! Be careful. Don't pry on the airbox itself; it is thin walled and could be damaged. Not much force is needed, just firmness and control.
Then similarly lift the assembly out of the front connectors. (Some list members report that it is easier for them to reverse this and take out the front ones first. If you do this remember to loosen both bands on the front connectors.) Remove the boots from the engine and the carbs and set them aside. Slide the carbs to the left to gain access to the throttle & choke cables.
Prop the carbs up with your knee so they don't fall. Loosen the choke cable bracket and disconnect the cable end.
Instead of detaching the throttle cables from the bracket, try using a ratcheting offset phillips screwdriver to detach the throttle cable bracket from the carbs. Then, disconnect the throttle cable ends, twisting the throttle grip to gain slack.