Removing certain tools with dailog shop?

Below is the script for a dailog shop. It is very similar to that found in roblox wiki here.

local dialog = script.Parent
dialog.DialogChoiceSelected:connect(function(player, choice)
    local stats = player:FindFirstChild('leaderstats')
    if not stats then return end
 
    local gold = stats:FindFirstChild('Gold')
    if not gold then return end
 
    if choice == script.Parent.DialogChoice.ChoiceA then
        if gold.Value >= 500 then
            game.ReplicatedStorage.AK-47:Clone().Parent = player.Backpack
            gold.Value = gold.Value - 500 
        end

While this script works, I want to make it so if you buy the AK, it replaces a certain weapon in your backpack (example, if you have a healthkit and a assault rifle in your backpack, buying the AK replaces the assault rifle ONLY).

Thanks!