While it is theoretically possible to cement your portable hoop into the ground, it is significantly more difficult than the process for in-ground hoops and defeats the reason for buying a portable hoop in the first place.
If you cut the base off and cement the pole into the ground, it won’t be as stable as it was before because most in-ground hoops come with extended poles that go multiple feet into the ground. You could simply bury your base, which wouldn’t be too hard, but this would shorten the hoop, so it might not be tall enough to meet the standard 10 feet.