Turn off “Exercise ring closed”

You have to turn off goal completions;

Settings/activity/goal completions.

No, it has nothing to do with the goal completions. You get the notifications no matter what. It’s a known bug.

There is no way to turn it off. Just another garbage Apple bug.

You don’t because you don’t work out.

The setting can be turned off and the bug still causes the ring closed notification on the watch.

I don't because my watch is set up properly.

Not on my watch,you obviously don't know what you're doing.