I hope next time learn how to use the search button before you create a topic like this because there many similar topics that already posted few days ago.
There are many guides out there but you need to make sure always verify the Electrum before you install.
Check this guide
https://bitcointalk.org/index.php?topic=5240594.0Many thanks. But I searched and I could not find one which specifically showed how you solve the problem of already having an Electrum wallet in an old PC and wanting to make sure your coins are only on your new PC and not accessibly anymore on the old PC.