mongodb delete one document code example

Example 1: mongodb delete all documents

db.collection.delete_many( { } );

Example 2: mongo delete all documents

db.bios.remove( { } )

Example 3: how to delete subdocument mongodb

db.getCollection('products').update({}, 
{$pull: {reviews:
{user: ObjectId("5f6e2e0b70eb0208fc84011a")}}},
{multi: true})