No, there's no option other then emptying.

There are plenty of pool treatments that leave long term residue. There is NO way to remove those from the equation, other than to start with new water. There is a sneaky way to drain, however: just do it at night, during rainy weather! And before you drain, you'll need to fill our the pool equipment info. If you have an AG pool, or a in-ground concrete pool, it shouldn't be too much of a problem. If you have a fiberglass IG pool, you'll have to be careful. If you have a vinyl liner IG pool . . . it may be a problem.

BUT . . .

Get the test kit, and then do the tub test, first! If you DO react to fresh water in the tub, then we need to investigate THAT, before you drain.

For a small amount of un-diluted dichlor, your best bet is probably Amazon. There are links in the Super Simple recipe page: http://pool9.net/ssr/. If you need dichlor for your pool, then Sams Club is almost always the best bet if you have access. Most of the dichlor sold by Walmart and Costco is diluted and blended . . . and some of the dilutants are potential problems.

Good luck!