@mishely1
I don't really see the purpose of turning off notifications for a forum but you can do that under the Settings in this forum. Select your username/avatar top right, go to My Settings/Notifications and Subscriptions, and disable or enable what kind of notifications you want.
If you simply want to stop receiving notifications for a thread you participated in, (ie. old thread), then go to that thread and select the three vertical dots at top of thread (or from one of your responses) and select "Unsubscribe from this topic".
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941