I must say I don't agree, and I think what HLab suggested is by far the easiest and best if the existing smallest rear sprocket is not 11T. Replacing a 12T cassette with a 11T one increases the highest gear by around 8%, to achieve same by fiddling at the front you need to replace the 50T by a 54T. Since all front shifts feel agricultural at best, it would just make it worse, if you haven't run out of front mech max range in the process already. A larger large front ring is also heavier, and usually more expensive, given the low price of 8 speed cassettes.
You don't need to break the chain to remove the chainset. However you may well need a new, longer chain if you put on a larger large chainring - assuming the current chain is just right. The other thing of course, is that you are far more likely to run out of rear mech wrap range by increasing the size of the large chainring (because you need to increase range by 4 to achieve the same effect as 1 at the back).
If the OP has a choice, it really is a no-brainer.