Hello, been a really long time since there was anything on this. I just ran into this problem myself. I may have found a fix at least it worked for me.
1. Go to connect.garmin.com if you're using a cell phone request desktop site.
2. Sign in, go to golf, then scorecards
3. Find the problem scorecard click the name of the course and at the top right there is a little trash can. Click and confirm
4. Go to the Garmin golf app and sign out then back in.
Problem should be solved!
Sad that deleting it on your phone but doesn't update until you sign out and sign back in. Such a SIMPLE fix GARMIN!!!.
Deleted the score card on my phone - still showed up. Went to the website and the card was gone. Signed out and back in on my phone and hey ho, the card has gone.
So basically, delete the scorecard on your phone, sign out of the golf app, sign back in - all should be well.
I didn't need to sign out, could have been a sync delay
Very helpful, thanks! FYI I didn't need to sign in/out of Garmin golf app. I noticed it wasn't deleted initially but then went to another part of the app and returned to scorecard screen and card was no longer there - probably just a sync delay between website and app
Use website login for Garmin connect, not mobile app