When an NCAA athlete (any sport) enters the Transfer Portal, that means they can be contacted by coaches at other NCAA programs about a possible transfer. It also means that their school has the right to not renew their scholarship for the following year.
Any other consequence of that (being removed from the college team, having name removed from college website roster, not being allowed to play in certain summer leagues) is not an NCAA rule. They also aren't automatically withdrawn from their college.
They would have the chance to return to the school the following year and continue progress on their degree. They would also be allowed to rejoin their team if their coach allowed it (obviously not likely, but possible).