Where did you get this little guy at such a young age? Is he a rescue?
For cleaning up urine spots, use an enzyme cleaner like Nature's Miracle instead of bleach. Bleach may actually be attracting him to those areas again.
Can you put the other litter box back where it was? If he starts using it again, I'd suggest very gradually, like a few inches a day, moving it to where you'd rather have it. Taking it away suddenly like you did could be part of the problem. 10 week old kittens have very small bladders and it's possible that by the time he realizes he has to pee, he isn't close enough to the basement litter box to make it in time.
Something else you could try is
Dr. Elsey's Kitten Attract litter. It has a very fine texture and some added herbal aromas that entice kittens to use it.
What kind of litter are you currently using?