when my son was in K1, he sometimes didn't want to do hw also, i was angry at that time, so i also understand your feeling right now. as my son started to have quite a lot of hw in K1 already, he can do hw by himself now once he knows how to write it, so give some more time for your child to accustom how to do it la.
what's more, did he need to write all the time in K1? some KG start to let the children to write words or letters in K2, of course he cannot write very good now, don't be too demanding la!!
i remember that my son's K2 teacher really told us no need to erase his handwriting all the time unless he writes it wrongly. coz always erase will discourage his confident.