If you're looking to avoid the salon and save money on products, you can purchase vitamin C powder that you can simply mix with your existing shampoo. If you don't have powder, you can even try crushing up tablets.
Mix one part of the vitamin C powder and two parts shampoo and mixed it into a paste. Then wet your hair and lather the paste onto your strands. Once your whole head is lathered and covered, put on a shower cap, drape a towel around your neck (to catch any drippage), and chill for about an hour.
Why does it work? To my understanding, most hair color (or at least the permanent kind) uses oxidative dyeing. The dye penetrates the hair shaft and polymerizes into larger molecular units, wedging itself in between hair cuticles and onto the cortex. This makes the dye chemicals more resistant to removal. You know how ascorbic acid oxidizes quickly? Putting an acid like vitamin C on hair that's been dyed loosens these molecular units, giving dye the chemical heave-ho.
The bottom line is you shouldn't be afraid to experiment — it can be fun to play around or switch things up. But it is always important to keep the health of your hair at the top of mind (pun intended). Use gentle solutions, and when in doubt, seek a professional's opinion. That's what they're there for, and in the end a consultation could save you much time and money than dropping your whole paycheck on products that might remove color.