Why can't I uninstall Norton Bootable Recovery Tool

I've had several problems since updating NBRT. Probably a co-incidence but I now want to uninstall it so that I can check on a step-by-step basis what's causing the problems, and reinstall it later.

 

I recently got help in updating it - see http://community.norton.com/t5/Other-Norton-Products/Norton-Bootable-Recovery-Tool/m-p/896867#M54033 but I now find that as well as having v5.1.0.26 I also have v4.1.0.15 .

 

Two days ago I only had one program showing and I uninstalled it with Revo (free).

 

I can't understand why it's come back and in 'stereo'! Can anyone advise me please? Thanks