How can eliminate a components class that already is in the cost of item?

In implementation  of Oracle R12 were created many classes of components, and today it became a big problem!
We need to group  some  classes of components to simplify the process of cost, and thus reduce our database and earn performance in the processes GMF.

Then, we need to group some classes of components creating a new (many old classes of components to a new class). We are using a fit (cm_adjs_dtl) to reset the values of the old classes and transferring this value to the new component class, technically it works ... however the old  component classes do not disappear from the system and are loaded for next month.