1. Delete items using the delete-item command and a key:

aws dynamodb delete-item 
    --table-name my_table 
    --key '{"id":{"S":"002"},"dateandtime":{"N":"1536898295"}}' 
    --region us-east-1
    --profile admin

Similar to update-item, for delete-item, you also you need to specify all the keys available using the key option.