Can't Delete Lightroom previews.irdata file

Hi,

I have a new problem with an old issue. I have read as many threads as I could on it and cannot seem to fix these issue.

I had been using LR4 and added new drives to my Mac Pro 2009 OS 10.6.8 w/48RAM

I started getting the the "LR encountered an error when reading the preview cache and needs to quit" message.

I have since installed OS Yosemite and installed LR5.2

I followed the instructions to delete the Previews.Irdata and then got this message

then this one

I have older catalogs from LR2,3 and 4 on another drive. I was able to delete some but not all.

I was able to delete the LR2 previews.irdata file but not the LR 3 and 4. This prevents LR from functioning. It launches but then gives this message.

Any Ideas.....please send my way. Thanks