memorized my seed phrase
Terrible idea, especially if you are not repeating your seed words every day.
Why is this? If my computer gets stolen all anyone needs to do is crack my password and they get my coins. I want to remove any trace that Electrum was ever on my computer. Can somebody tell me how to do this please?
You should format your hard drive and reinstall fresh operating system if you want to be sure to have no traces of electrum wallet.
Another option is to use linux os on usb stick, something like TailsOS won't leave any traces on your computer.