I'm having a hard time getting my Plex signal to activate, so I'd like to cancel my subscription.

I’m having a hard time getting my Plex signal to connect, so I’d like to cancel my subscription.

I’m guessing you are looking for link: https://plex.tv/subscription

If you could explain what you mean I can try to help you with your issue.

Any account changes you need to make can be done from your account settings page: https://plex.tv/subscription (or plex.tv -> My Account -> Settings -> Subscriptions).