Under engine cleaning.
 

Hi, can u take off the plastic black guard thingy under the engine and those 2 aluminun looking bracers that are connected to which looks like the rear torsion bars which looks like u just need to unbolt those bolts out. I would like to polish and clean those parts up.? Is it safe too? Or are those in there to keep rear alignment which means i would have too realimgent if i took them out?

You can remove them. Porsche calls them struts, but they're commonly called diagonal braces, here, in the Bentley, etc.

I have only done it with the car on jackstands and the weight off the suspension when I did the filter and fluid change on my tiptronic.

If you did it with the suspension weighted, I think you may have trouble getting everything to line up when you went to reinstall it.

If you're cleaning the engine, be sure to cling wrap the electrical stuff. Porsche makes a special point to be sure to protect the coil paks and the O² sensor connectors in the engine cleaning procedure in the Factory Repair Manual - 10 01 29 Cleaning the engine.