Mothballs in the attic, get a few boxes put them in socks with strings
attatched in case you want to pull them out later.

Leave them one hole to get out and do something to the hole so they
cant get back in, like line area with sheet metal so there is nothing to
grab onto, or PVC pipe for a slide out.

I had one squirrel like that he ate 4 different holes in, id seal up a
new one he would start again, finally I trapped him in a have a heart
trap. Remember its their home now you are suposed to leave, they were
there first.

I also got a fewpacks of gopher bombs, Giant Destroyer, I put them in a
coffee can and the coffee can in a metal bucket with a bit of water in.
They burn hot like flares , put it in the basement, lit, went outside
and saw coughing squirells come running out. But this will kill you,
you have to leave for many hours 4-8 then carefully air out the house
without killing your self. Have fun, get a pellet gun if all fails