It should be possible to delete shared posts in the "..." options, not after clicking on the number of shared posts.
The function is good but it makes no sense where it can be found now. Nobody sees the option to delete a shared posts and would look for it there.
From my point of view it makes sense as soon as there is more than one share of the same content. If you put the option to the share itself on the timeline - which share is going to be deleted? Additionally, you can't delete shares of other users.
I have to admit that the function is quite hidden but I can't think of an easy way to change this.