I dont think it works that way marcus, once its on the timeline its there to stay i think... unless you manually delete it. 

Marcus have you tried to reproduce the issue on our demo? 

I mean I join a group right and post on the group wall some post then I delete that post. It's no longer shows on the group wall. However it does show on dashboard which means all my followers and buddies will see it :)

Yes, I understood the issue, but have you checked whether it exists on our demo website? 

Same happens to videos. You delete the video post but the video can be found in my videos :) Gonna check on demo later

Yes, I already noted that we have on our roadmap to differentiate the content from groups and other site content. 

OK thanks buddy!