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.
Technically if you want a large tip you can cut the bumper.
You can choose a tip for your car here:
Black, Chrome, Dual Exhaust Tips at CARiD.com
They are universal and may fit on any car, just choose the rite size.
Let me know if you have any other questions!