How many did you get?
If you're concerned about the foulbrood spores - scorch the insides.
An easy way is to stack them up straight on some bricks on the corners.
Wad up a bunch of newspapers, toss them in, light the bottom.
Do it away from anything that might catch the sparks coming out the top.
Have a garden hose ready in case the wood starts to actually burn.
Some heavy charring won't bother the bees.
It might reduce to life of the box alittle, but they're free and they'll be sanitized.
Goodluck.