How to make 1/4 cut in Siemens NX?

Question

Siemens

There is an oblong detail. It is necessary to cut a quarter out of it.
This is my first time dealing with NX.
The end result is a conversion with this cut to formats understood by 3Ds Max and Cinema 4D.
PS Before that, I tried to make a cut in 3Ds Max and Cinema 4D. But, because the model is quite complex (several thousand individual parts and about 30 million polygons), I did not see an adequate result. Made on the basis of the combined model by subtracting the primitive.