Most simple way I could think of is to load the big world file
SysDyn_{9A103CC2-4190-4DB3-9618-0419E5445AAD}.lrentdat
into a hexeditor and search for the string
"G3_Myrtana_Vanguard_Magic_Barrier_01".
At its first occurrence replace the "_01" by "_02" for example.
Did not test this but should work.
You also might search the forum; iirc the CPT did some manipulations to the barriere, too.
btw: I don't see any good reasons to remove it; its one of the most important features in Gothic 3, imho.