How to remove an item on nested list in .NET Core using C#?

I have to remove an item from the nested list using C#. This is my list:

{
    "Name": "CC",
    "Categories": [
        { "description": "Visaa", "payCode": "v" },
        { "description": "Master", "payCode": "m" }
    ]
},
{
    "Name": "paypal",
    "Categories": [
        { "description": "paypal", "payCode": "p" }
    ]
}

I want to remove this category list from CC type:

{
   "description": "Master",
   "payCode": "m"
}

After that, my list should looks like this:

 {
        "Name": "CC",
        "Categories": [
            { "description": "Visaa", "payCode": "v" }
        ]
 },
 {
        "Name": "paypal",
        "Categories": [
            { "description": "paypal", "payCode": "p" }
        ]
 }

I tried the following but not sure how to do it to get the above list

payments.Find(x => x.Name == "CreditCard").PaymentOptions;

payments.Find(item => item.name == "CC")
        .Categories.Remove(cat => cat.payCode == 'm');

You need to remove the element from categories object, here an example...

using Newtonsoft.Json;

namespace tests
{
    public class Testing
    {
        public void Run()
        {

            var stringPayments = "[{\"Name\":\"CC\",\"Categories\":[{\"description\":\"Visaa\",\"payCode\":\"v\"},{\"description\":\"Master\",\"payCode\":\"m\"}]},{\"Name\":\"paypal\",\"Categories\":[{\"description\":\"paypal\",\"payCode\":\"p\"}]}]";
            var listPayments = Newtonsoft.Json.JsonConvert.DeserializeObject<List<Payment>>(stringPayments);
            
            //List before remove
            Console.WriteLine("List before remove");
            PrintPayments(listPayments);

            //List after remove
            listPayments.Find(p => p.Name == "CC")
                            .Categories.RemoveAll(c => c.Description == "Master");
                            
            Console.WriteLine("\nList after remove");
            PrintPayments(listPayments);
            
        }

        public void PrintPayments(List<Payment> listPayments)
        {
            Console.WriteLine("---------Start-----------");
            foreach (var item in listPayments)
            {
                Console.WriteLine("- Name: " + item.Name);
                Console.WriteLine("---- Categories ----");
                foreach (var category in item.Categories)
                {   
                    Console.WriteLine("---- Description: " + category.Description + ", Paycode: " + category.Paycode);
                }
                
            }
            Console.WriteLine("---------End------------");
        }

    }

    public class Payment
    {
        public string Name { get; set; }
        public List<PaymentCategory> Categories { get; set; }
    }

    public class PaymentCategory
    {
        public string Description { get; set; }
        public string Paycode { get; set; }
    }
}

With a LINQ statement you can only query data, you cannot change the queried data

If you want to change the data in local memory, you'll have to fetch references to the data, and then enumerate the fetched references to change it.

If the data is somewhere else, for instance in a database, You need special methods to change the data. If you use Entity Framework, you'll have to query the complete items (= not use Select), enumerate the fetched data to change the data and then call SaveChanges.

Back to your problem.

As you are using Find, I assume you are using something like Entity Framework.

You forgot to give us your classes. I think you have classes similar to the following:

class PaymentCategory
{
    public string Name {get; set;}
    public string PayCode {get; set;}      // or even better: enum?
}

class PaymentMethods
{
    public string Name {get; set;}
    public virtual ICollection<PaymentCategory> Categories {get; set;}
}

Requirement: Given a sequence of PaymentMethods X and one PaymentCategory Y, give me the sequence of all PaymentMethods X, without the PaymentCategory Y in property Categories.

How about this:

IQueryable <PaymentMethod> paymentMethods = ...
PaymentCategory categoryToRemove = ...

IEnumerable<PaymentMethod> paymentMethodsWithoutCategory =
    paymentMethods.Select(paymentMethod => new PaymentMethod
    {
        Name = paymentMethod.Name,

        // keep only those PaymentCategories that have not Name / PayCode
        // equal to the ones in categoryToRemove
        Categories = paymentMethod.Categories
            .Where(category => category.Name != categoryToRemove.Name
                            || category.PayCode != categoryToRemove.PayCode)
            .ToList(),
     });

In words: from every paymentMethod in the sequence of paymentMethods, make one new paymentMethod containing the following values for the property:

• Name: use the name of the paymentMethod
• Categories: take every paymentCategory from the sequence of Categories in the paymentMethod that have either a Name or a Paycode different than the Name / Paycode in categoryToRemove. Make a list from this.