local keycard = game:GetService("where it is located"):WaitForChild("nameofpart")
local ppro = game:getService("where it is located"):WaitForChild("name of proximity")
ppro.Triggered:Connect(function(Player)
keycard.Transparency = 1 # or try use deleted keycard:Destroy()
end)
CollectionService:GetTagged() returns an array of objects tagged with the specified tag. You have to loop over Tagged and connect the Triggered event to each ProximityPrompt.