[s-cars] NAC (other than my S6 is in the barn) How do I SAFELY dispose of a gas tank?

[LL - NY]

Looking for collective list wisdom.

Found an old gas tank with gas in it in my new (to me)
garage. It appears to have about 2 - 3 gallons in it. I plan 
to siphon the remainder, but how do I deal with the fumes?

I have a salvage guy coming this week to take it, IF it's empty.

TIA,

Scargo