Thanks for checking back.
No worries, I understand commands can sometimes be tricky, but I'll help you through it.
The reason the command isn't working is because it's being typed incorrectly. Take a look at the screenshot from my computer; this is the correct format. Just type it exactly as shown, without any additional characters.
In the screenshot you sent, you added an asterisk at the beginning, but the original command doesn't have one there.
Remove-Item -Path "$env:APPDATA\Microsoft\Windows\Notifications*"