Cleaning Used Cat Tower

I just received a used cat tower and was wondering if it is truly safe for
my cats? I was told that it would be ok to bleach it before giving it to my
cats. Has anyone else here ever gotten a used tower and safely been able to
allow their cats to use it? I saw that one of the cats in this home was
pretty healthy (awaiting FELV test) and the other was a feral so it is
unknown how healthy that one was. The woman had adopted the one black cat we
found from the Humane Society while the other one she brought in from
outside. One of the neighbors said he was a longer haired cat which looked
like he was a bit large. Both cats were displaced by a fire and the one we
found we were able to get into the adoption system of a local rescue group.

The cat tower is now on our back porch so I was wondering what besides
bleach do I need to use in order to sterilize it? The tower is kind of tall
(a little over 6 feet) but it does need some vacuuming and such but it was
one of the few things which survived the fire besides both cats.