Answer:
Drain the radiator first then remove the hose connector from the hose you want to replace. Once loose try pushing on the hose with a twisting motion firts to help release its hold on the pipe its connected to. If it is really stuck you can stick a screw driver under it. Just be careful not to hurt the metal connection.
Now take a scotch pad and clean the connection off really good. Cut to fit the new hose and test fit it in place. Then tighten down the connections. If you had the original style clap style connectors I suggest you replace them with new hose clap style connectors. They original ones live in the heat and they can fail to hold now that they are old and heat tempered.
Refill the radiator with regular water and run the engine to temperature for about 10 minutes. Check for leaks and if none are present then drain it again and refill with a good anti freeze.