If I specified that there was a bin involved, using 'throw' alone sounds more natural. If you are not referring to a bin, then you should use 'throw away'. For example, (i) 'he threw his half-eaten sandwich into the bin' - using just 'threw' because you are specifying that a bin is involved and (ii) 'he threw away his half-eaten sandwich' or 'he threw his half-eaten sandwich away' using 'threw away' because you are not referring specifically to a bin. As for throwing something into the street, that's more complicated. If you mean that he was littering, i.e. he was too lazy to find a bin, so he just discarded chocolate bar wrapper in the street, then you would probably say 'he just dropped his chocolate bar wrapper'. 'Just' indicates laziness and 'dropped' indicates that he actively chose to litter, rather than an accident, for example 'his chocolate bar wrapper fell out of his pocket into the street'.