I got two database table like this

Schema::create('folders', function (Blueprint $table) {
            $table->id();
            $table->string('name');
            $table->foreignId('parent_id')->nullable()->constrained('folders')->cascadeOnDelete();
            $table->string('path')->nullable();
            $table->foreignId('user_id')->nullable()->constrained('users')->cascadeOnDelete();
            $table->timestamps();
        });
Schema::create('files', function (Blueprint $table) {
            $table->id();
            $table->string('name');
            $table->string('path')->nullable();
            $table->string('size');
            $table->foreignId('user_id')->nullable()->constrained('users')->cascadeOnDelete();
            $table->string('image_url')->nullable();
            $table->foreignId('folder_id')->nullable()->constrained('folders')->cascadeOnDelete();
            $table->timestamps();
        });

I try to use Model Event but I not really understand it

Now when I delete a folder and, in that folder, have a file so I want to remove a file when a delete is removed. File is I upload from PC but folder just create by link does not create a physical folder in PC.