Q: like does not remove from post schema like does not remove from post model
likeSchema
    .findOne({$and: [{post: postId ,user: userId}]})
    .exec((err, result) =>{
        if (result) {
            db.likeSchema
                .findOne(
                    { 
                        $and: [
                            { post: postId },
                            { user: userId }
                        ]
                    }
                )
                .exec((err, like) => {
                    db.likeSchema
                        .findOneAndUpdate(
                            { 
                                $and: [
                                    { post: postId },
                                    { user: userId }
                                ] 
                            }
                )
                .remove()
                .exec(() => {
                    db.postSchema
                        .findOneAndUpdate(
                            { _id: postId.postID },
                            { 
                                $pull: { 'likes': like._id }
                            }
                        )
                        .exec((err, post) => {
                       
                        })
               })
            })
        }

const likeSchema = new schema({
    post: { type: schema.Types.ObjectId, ref: "postSchema" },
    user: { type: schema.Types.ObjectId, ref: "userSchema" }
})
const postSchema = new schema({
    owner: { type: schema.Types.ObjectId, ref: "userSchema" },
    text: String,
    image: String,
    comments: [{ type: schema.Types.ObjectId, ref: "commentSchema" }],
    likes: [{ type: schema.Types.ObjectId, ref: "likeShcema" }],
    date: { type: Date, default: Date.now }
}); 


A: Try this code
If you want to remove the 'like' in the 'post',you should delete its document.
LikeModel
        .findOneAndDelete({post: postId ,user: userId})
        .exec((err, like) => {
            PostModel
                .findByIdAndUpdate(like.post,
                    { 
                        $pull: { 'likes': like._id }
                    }
                )
                .exec()
                .then((err, post) => {
                    console.log(post)
                })
        })

UPD
Also don't forget to register your schemas
const LikeModel = mongoose.model('Like', likeSchema)
const PostModel = mongoose.model('Post', postSchema)

