If by chlorine water, you mean chlorinated tapwater, then yes you can leave a bucket of tapwater (that contains chlorine) outside in the sun for a few days to get rid of the chlorine. You can also aerate the water for a couple of days and it will drive the chlorine out of the water.
If you have chloramine in the water, then you need a dechlorinator to break the chlorine/ ammonia bond before you can use it for fish. Chloramine is a mixture of chlorine and ammonia and it does not break down as quickly or easily as chlorine on its own.