You said "I hastly made a Bee vac and then went to this house"...what type of vac was this?
If you can't get to the comb and brood of the colony then about the only way to remove them is a regular trapout or a Cleo Hogan one. Killing them inside the wall (spraying) is problematical in that unless you use something *really* deadly to them you won't kill them all but rather just make them sickly which may result in them dieing a slow death. The problem afterwards, whether they're quick killed or slowly killed, is that if you have 15 pounds of bees, brood, honey, pollen, wax, etc., in the wall...well, it's going to be something kind of like a 15 pound dead dog hanging in there. 25 pounds....ditto and so forth and so on... It can make a mess.
Ed