You can buy back ships and CCU upgrades, and you will know because when you melt them they will appear in your, “BUY BACK PLEDGES.” Do note that if you have SQ 42 or a game package attached to that ship, you will still need a ship in your HANGAR with a game package to play Star Citizen.
I made a post about this during the last sale and unless things have changed, it should still be valid.