Is there a way to delete all of my old (all is also fine) posts on my personal Google+ profile without deleting my Google Plus account? 
Delete all Old Google Plus Posts
google plus
Edit: Google+ has introduced an activity viewer, and I decided to automate purging posts, comments, and plusses.Go to https://plus.google.com/apps/activities/Click on Posts, Comments, or the set of activities you want to remove.Enter this code into the console to scroll to the bottom of the page:var intervalIDScroller = window.setInterval(function() {    document.getElementsByClassName(mUbCce fKz7Od)[document.getElementsByClassName(mUbCce fKz7Od).length - 1].scrollIntoView(false);}, 10);Once it has reached the bottom, enter this code into the console:clearInterval(intervalIDScroller);var intervalID = window.setInterval(function() {    if (document.getElementsByClassName(mUbCce fKz7Od).length === 0) {        clearInterval(intervalID);        return;    } else {        document.getElementsByClassName(mUbCce fKz7Od)[0].click();        document.getElementsByClassName(RveJvd)[3].click();    }}, 10);Let it sit overnight or for a few hours. You can change the 10ms interval if you are adventurous.Be careful though, this may remove things you may not want it to. And don't enter code into the console unless you understand what the code does (as the self XSS warning in the console explains).Old answer:I had to delete every single post. The Google Settings allows for you to delete all of Google+ but not only the posts.