MOVE A STUDENT TO ANOTHER GROUP AND DELETE HIM FROM AN EXISTING GROUP

Hello,
You can follow these steps:
Find your students: Go to "My Students" and then "All Students."
Select the students: Check the boxes next to the students you want to move.
Remove them from their current group: Choose "Remove from all groups" and click "Apply."
Add them to a new group: Select the same students again, choose "Add to groups," and then select the desired group.

I hope this helps!