Thomas ,
Since he says that "We dont use it "which means that he doesnot have partitioned table at all

I guess that his Q was not make the partitioned table as non-partitioned table instead he wanted to disable Partitioning option itself.(Hope my understanding was right)

If that is the case ,Instead of EE edition, Oracle Standard Edition can be used which doesnot have feature of

Oracle partitioning - For database over 100 gigabytes

or using Orainstaller we can deinstall Oracle Partitioning option,I guess.

Regards
Chithra