If like every other GM, rears are on with double sided tape and fronts have clips that snap into the grille.
First thing to do is buy the bowties and verify how they are mounted. The stick-ons are fairly easy to remove. First use masking tape to mark the 4 sides of the bowtie for exact positioning once removed. Then using small diameter nylon fishing line and "sawing" up and down to separate the backing tape from the body. Other methods include a using a hairdryer (I'd stay away from a heat gun for fear of damaging the surrounding area) and ently prying off as heat is applied using a plastic trim tool or wood popsicle stick.
Fronts are different and you can remove them the hard way or the dealer way. Real easy is most Chevy bowties have 4 mounting clips.....good news is you can reach some by sticking fingers through the grille.....bad news is you (at least I) can't reach the top one for release. You can try your luck releasing the ones you can reach and try to wiggle the last one(s) free. The hard way is to remove the grille usually by removing the engine compartment shroud to expose mounting screws then the grille can be pulled forward and the mounting clips will release...tried it once on the Silvy and never again too much chance of breaking the $400 plastic grille if one of more of the clips fails to release.
Then there is the dealer way which I have successfully used on a '15 Camaro, '15 Traverse and '16 Malibu...it destroys the OEM bowtie/mounting plate, but quickest and safest way to remove old one and to prevent damaging the grille. First as a precaution use masking tape on surrounded painted surface. Then taking a butter knife or screwdriver, pry the thin glued on original gold bowtie insert from the chrome mounting plate to expose the mounting clips and then release them prying with a screwdriver (or clip off the backs with a cutting pliers). Pop in the new mounting plate with the black bowtie, can be done in less than 5 minutes.