If the other half of the decayed tooth is still in the gums it is better to get it extracted.
Permanent teeth can sometimes improve its position on its own providing there are no blockages.
The best thing is to get an xray done to check that there are no blockages (ie extra tooth or root remnants) that is preventing it from coming down in the correct position.
If there are no blockages, the rotated tooth can be corrected with braces later on. I hope this helps.
Good luck.
Best wishes; Dr Sylvia Tan