Can you explain more about moving them away? Will they move to another home? Will I be playing with the sons or with the parents then?
You can also move the parents away without going into Edit Town. Have one of the parents use a cell phone or computer and chose "Move." If you have enough money, you can choose a new house for them to buy and it will come out of your household funds. Then you just choose which Sims are moving out and make sure the house with the sons is the active household. When that's done, the parents will just leave the house and go to the new one. They will disappear from the left side of the screen and you will no longer control them. If you don't have the money, you can still do this same thing with moving them, except instead of choosing a house for them, you click the "Kick Out" option on the screen where you choose who is moving. They will still leave the house and your control, but they will find their own house to live in. It can be any house in town that is vacant. They will just move into it and nothing is taken from your household funds. If you want to know where they will be living, you'll have to follow them when they leave. Use the pause feature to keep up with them because they go pretty fast.
Now, if you want them to just die, you can do what Swede said and trigger their age progression with ctrl-shift-C "testingcheatsenabled true." Once testing cheats is turned on, you can shift click the active Sim and select "Trigger Age Transition" and if the Sim is an elder, the next age transition is death. They will just peacefully die and Grim Reaper will come for them. It's easy and painless.