Need context, who is saying what to whom? is it forma or informal? Is it singular or plural. Males or Females. This as I see it is the biggest problem with clozemaster
It seems to me that it’s a command to “usted” to throw the papers in the basket (presumably throw away the papers in the wastepaper basket). If it was a command to “tú” it would be “echa”, but “eche” is the third person singular in the subjunctive, also used for commands.