Hi,
you should be start from scratch with the given WBS element, by deleting the "Investment Profile" in the assignment tab of the WBS element. SAP should then delete the AUC as well.
You might have to remove the assignment to the Investment program first, as well.
Save and start again, by assigning once more the "Investment Profile", etc.. Only works without any postings/settlements. So you have to reverse any previous settlement runs first.
Hope that was helpful,
Steffen