The halacha seems to be clear that if one finds chametz on Pesach (and it is not chol hamo’ed) he should cover it until he can burn it on chol hamo’ed. If he sold his chametz before Pesach then I assume he can’t burn it because it’s not his. My question is, can he move it with his body (tiltul b’guf) to the place where the rest of his sold chametz is being kept? If not, why?
We are not allowed to move it, but something should be placed over it, (a bucket etc.) so we will not see it. then on chol hamoed we can deal with it. The reason we may not move it, is because we might come to accidentally eat it, since we are used to eating chometz all year long. Regarding what to do with it on chol hamoed itself, there are different options. The preferred one is to actually burn it. Even though it technically belongs to the gentile, he will not care at all if you burn it, because he knows that he is buying it only for halachic purposes, and he will not mind losing a bit of the chometz that he bought. If this is difficult for you, you can also move it to the place that was sold to the gentile.
Shulchan Aruch 440-2, M:B ibid 13, Shevet Halevi 9-116, MIkroey Kodesh (Pesach) 1-74.