I would advise against this. Using channel lock plies (unless modified in some way to access the cutouts of a lockring) to try removing a lockring and cog will probably just end up ruining both.

OP, if you'd rather not invest in any additional tools to do the job yourself, paying a bike shop to swap out a cog shouldn't be expensive or time consuming.
Also moving form a 48 to 52 tooth chainring is moving the ratio up, not down, which means it'll be harder to pedal. Reducing wear by using larger gears usually refers to the size of the rear cog, you don't see any less wear on an extra 4 teeth up front. Also just having 5 holes on the chainring doesn't mean it'll match because the BDC may not be the same. Better off just checking out a LBS.