Wait until he is out foraging - usually about an hour after dusk & then seal the entrance & hope.
I had one take up residence under my backyard metal shed. It is up on piers at one end & I didn't backfill - at first. Once I realized he was there, I put gravel & dirt all around to seal the entrances. Of course, that was no challenge for him & he made 2 entrances. Then I did the above & waited one night until 11 or so & put rocks all around to foil his digging back in. Surprisingly, it worked. No smell so I assume he was out & I didn't block him in.
Maybe I just got lucky so your results may vary.
Ian