Is there a way to make a block disappear after a certain amount of time?

To make an Instance disappear after a given period, it is of best practice to apply DerbisService to your Script. Using the AddItem function of said Service allows the user to schedule a removal of an Object after a provided window. AddItem is also ran on a separate thread, meaning it will not interrupt your program and yield the Script; it will also ensure your program does not raise an exception if the Instance is unexpectedly null.

local DerbisService = game:GetService("Derbis")
local Part = workspace.Part

DerbisService:AddItem(Part, 60*5) --// Five minute window before removal

A simpler approach:

game.Derbis:AddItem(workspace.Part, 60*5)

This function is equivalent to Instance:Destroy(), meaning the Object will be permanently removed unless the Instance of reference is a clone and can be replaced upon re-loading said map. Otherwise, it is suggested you set the Parent of an Object to nil if you wish to remove it and reuse it again. You can use the delay function to gain the same effect as AddItem if you wish to do this and still run uninterrupted code

local Part = workspace.Part

delay(60*5, function()
    Part.Parent = nil
end)

--// Set the Parent back to workspace when needed