I have got several games in my opengame list.
How to quit or delete them?

Pootch

The Open Games tab lets you join games created by other players. You can join them by clicking on them and then "Join Game", but if you don't want to play you can safely ignore them. You don't need to delete them.

Out of interest: Are games created by blacklisted players automatically filtered out?

Players on your blacklist are prevented from joining open seats in games you create. They are automatically filtered out - they never even see the game appear on the Open Games page.

I thought it would work the other way round as well, so that games created by players I have blacklisted never show up on my own Open Games page either.