I'm not following. Are the old parts that had the locations discontinued or are they being moved to new locations? If they are still valid parts but are being assigned new locations can't you just upload the new locations?

If you are looking for a way to just temporarily blank out some item #s (to prevent the issue of having two items with one bin loc while you rearrange and organize) what I have done in the past is upload a unique character to the items #s that I want to remove the bin loc from (I typically use an asterisk) and then use UT-K-B Search and Replace to replace the asterisk with a blank space. Not sure if this is the correct way but it is a workaround that has been effective for us during large rearranges, at least preventing a bin loc from appearing on anything and eliminating the risk of someone accidentally pulling the wrong item while we work through the process.