so ive scoured my drive looking for all of the little areas renoise installed too, and have deleted.
when trying to reinstall it gets all the way to the drive selection page and when selecting the normal drive it says "you cannot install this software on this volume. (null)
solution: go to the finder and search for renoise. go through and delete everything that comes up with a system path to an area with the prefix directory “library”.
makes sure you get the one in reciepts also.
now when you reinstall 1.5 choose a different folder to install renoise to, and all will be fine.
also, make sure you dont mix up the 1.5 and 1.5.1 files, their all named the same,
and could have you end up repeating the above process several times.