Simplify way to delete branch after merge

More often than not, I tend to forget to delete my branch on merge.

This can cause quite some pain, as there is no easy way to delete my branch post-merge. 

I need to go to the branch view, look for my branch or filter accordingly and then remove it, trying not to mix up the rows and accidentally delete someone else's branch.

What would help a lot, would be a way to delete my branch post merge, right there and then on the pull request. A very simple way would e.g. be to simply turn the merge button into an delete-branch button, if the branch after a merge has not been deleted. 

See attachments below