Error the incoming request has too many parameters. The server supports a maximum of 2100 parameters.

This is because, at each iteration of your for loop, you are adding a new parameter to the command.
You could try:

try
{
   int NumberOfTimesToExecuteDeleteCommand = (int)Math.Ceiling((double)parametersCount / restrictedSize);
   cmd.Parameters.Add("@pFieldValues", SqlDbType.<enter your desired type here>);
   for (int i = 0; i < NumberOfTimesToExecuteDeleteCommand; i++)
   {
      cmd.Parameters["@pFieldValues"].Value = fieldValues.Skip(i * restrictedSize).Take(restrictedSize));
      cmd.ExecuteNonQuery();
   }
}

Or you could issue a separate delete command for each value, eventually wrapped in a transaction.

I am an anti-ORM person, and I personally would create a Stored Procedure to do this and pass in your "parameters" as a delineated string.

Without knowing what type the field values are in your program or database and what they may contain; I am going to base this off of a common type (string or numeric) and I am going to just use a comma as a deliminator

Here is a sample SQL Stored Procedure

CREATE PROCEDURE dbo.MyTable_Delete_ByIdentifierAndValues (
	@Identifier	INT, 			-- choose appropriate data type
	@FieldValues	NVARCHAR(8000),
	@Delineator	NCHAR(1) = ','
) AS 
BEGIN
	DELETE	MyTable
	WHERE	identifier = @Identifier
	AND	[value] IN ( SELECT value FROM STRING_SPLIT(@FieldValues, @Delineator);
END
GO

And here is the rough C# code to utilize it

SqlConnection conn = new SqlConnection(connectionstring);

string Delineator = ",";
int RowsAffected = -1;

SqlCommand cmd = new SqlCommand("dbo.MyTable_Delete_ByIdentifierAndValues", conn);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("@Indetifier", /* identifier */);
cmd.Parameters.AddWithValue("@FieldValues", /* FieldValues.ToDelineatedString */ );
cmd.Paramaters.AddWithValue("Delineator", Delineator);

conn.Open();
RowsAffected = cmd.ExecuteNonQuery();
conn.Close();