Standard prefilters (stages 2 and 3) would remove most of the cholrine from tapwater.
However, if your water supply is treated with chloramine (in place of or in addition to chlorine) you might want to look into getting prefilters that remove chloramine - specially if you are planning to use the wastewater for fish.
The chloramine version just uses different filter material for two of the prefilter stages. Otherwise it is identical to the regular RO/DI unit.
For example (may vary by model)
Canister 2 will use Catalytic Carbon instead of the standard Stage 2 Carbon Block.
Canister 3 will use a ChlorPlus insert instead of a standard Stage 3 Carbon Block.
If your water supply is treated with just chlorine, then you do not need the chloramine upgrade/kit. You can just let the wastewater sit in an open container with a circulation pump overnight and the chlorine would dissipate.