ConvexHull directory still there. Got an error

git checkout master
Switched to branch 'master'

git status
nothing to commit (working directory clean)

git merge next
Updating 82c5f29d..895ad746
warning: unable to unlink ConvexHull: Permission denied
Fast forward

src/Changes.txt

@@ -97,6 +97,7 @@ To do
 
 ------------
 Need help
+ - git has an empty ConvexHull submodule on master or next.  How to remove it?  
  - The C++ interface needs work.  Give it a try and make it better.
  - Set up debian build. 
    Please keep debian files in config/ and project/debian/