BUG #14437: Fix delete of help proxies

The previous version was iterating over the number of proxies and
deleting a help proxy at each iteration.  I suspect this caused the
index <-> proxy reference to update making the iteration over number
of indicies invalid.

Instead create a list all the proxies to delete first and then delete
them without referencing proxies by index.

Change-Id: Ic2fee72a41e19308f80cfa82427ada55ff3331c3