When editing Delivery/Delivery Template there is an "Include" menu which allows to pick up Pers. block etc.
The question is how to modify it's elements? For instance, I'd like to remove Unsubscription link from here as it shouldn't be used in our environment and we have our own unsubscription pages.
The 3 items we can see on your screenshot cannot be removed from the drop down menu. If you use other personalization blocks, they will be added to that list as well.
What you can do is modifying the personalization block itself from Resources > Campaign Management > Personalization blocks. For example by setting it empty, or by inserting your own code into it.
Hope this helps,