How to make transaction of some ether in Buyer Seller type of contract?

Question

In this I have set modifier (msg.sender == sellerAddress) which is not valid. But in this scenario, I want to allow only and only sellerAddress to take ether from my contract. How can I allow only seller address to do this. As well as which kind of inputs I have to enter while executing contract?

contract ContractDemo {
    address public buyerAddress;
    address public sellerAddress;
    uint public price; //price or charge for delivering parcel

    modifier onlyBuyer() {
        require(msg.sender == buyerAddress);
        _;
    }

    modifier onlySeller() {
        require(msg.sender == sellerAddress);
        _;
    }

    constructor(address payable _sellerAddress) public payable {
        buyerAddress = msg.sender; 
        sellerAddress = _sellerAddress;
        price = msg.value;
    }

    function deliveredParcel(address payable _seller) onlySeller public payable returns(bool) {
        require(msg.value == price);
        _seller.transfer(msg.value); 
        return true;
    }
}

Answer 1

Call the deliverParcel function using the seller address then the modifier will work fine. The function will be like

function deliveredParcel()onlySeller public payable returns( bool) {
    require(msg.value == price);
    sellerAddress.transfer(msg.value); 
    return true;
   }

OR Change the modifier to this

modifier onlySeller(address seller){
    require(seller == sellerAddress);
    _;
}

Respectively the function will look like this

function deliveredParcel(address payable _seller)onlySeller(_seller) public payable returns( bool) {
    require(msg.value == price);
    _seller.transfer(msg.value); 
    return true;
   }