Why is my App Updates linked to my wife's AppleID? I can't change it I recently purchased a mac pro w Yosemite.  I left my wife set herself up as an additional user, which later I removed.  Now 3 apps (numbers, Keynote and Pages) which need to be updated are listed under her apple ID and requires her password.  Being my laptop, I want to correct this and use my ID.

Unfortunately the OS doesn't allow me to delete them. When I tried to re-purchase them, it only allows me to update the apps, and then shows my wife's ID and wants her password. I can use her password but would rather correct the problem.
if she 'bought' them, even on 'your' machine, they are tied to her Apple ID. You would need to re-purchase under your own ID. 

App Store purchases are not tied to a machine, they are tied to an ID

… or set up Family Sharing, which would allow you both to download/use any app purchased under that share, without impinging on general privacy.