When you have a dead colony, it is best to clean it out before it warms up.
First look where the cluster is and try to determine how they died. Starvation normally looks like a bunch of bees dead in the cells with their butts looking out at you. If all the bees were gone, it was varroa. If the cluster was separated it could have been a virus. One reason they can die is having an old queen. A beekeeper should never run a queen through more than one winter.
Clean out any loose bees, use a bee brush. Clean off the bottom board.
Bring a box with you to put the dead bees in. Don't leave the debris near your hives. It can draw skunks. Also the debris will make the grass grow faster and you will have to cut it more.
When you are done cleaning it out. Seal up and entrances to keep other bees from robbing your honey that you can feed to a package or a divide.