Cubit 15.7 User Documentation
There are two commands used to remove partitions:
Partition Merge {Curve|Surface|Volume} <id_list>
The command combines existing partitions where possible. This command is similar to the composite create command. The difference is that this command is special-cased for partitions, and will result in more efficient geometric evaluations. If all the partitions of a real solid model entity are merged, such that there is only one partition remaining, the virtual geometry will be removed, and the original solid model geometry will be restored to the model.
The CUBIT delete command can also be used for removing partitions. See Deleting Virtual Geometry for a description of its use.