Exhaust tips are usually attached with a clamp, so you should be able to remove it with a screwdriver or a wrench - it is very easy to do. In some rare cases exhaust tips are weld-on, in this case you would need to cut it.
In order to get the right exhaust tip you would need to match the inlet of the tip with the outlet of your exhaust pipe. it may be somewhere around 2"-3" (you need to measure it by yourself).
For example the outlet of the exhaust pipe on your car is 2.25" it means that you need to choose an exhaust tip with the inlet size 2.25". The outlet of the tip may be bigger, just make sure it doesn't interfere with your bumper.
On my 2015 SL the chrome tips are welded to the exhaust pipes.
I like the looks of the original chrome tips, but they were recessed so far under the bumper you could hardly see them. My local muffler shop only charged me $40 to cut the exhaust pipes and put in some extensions to move the tips out a few inches.