C:\programsfiles\windowsapps\apple.itunes...I keep getting this popup on my pc. how do I get rid of it? thanks.

The general troubleshooting advice when iTunes fails to install properly (and reinstalling or repairing it does not work) is to remove not only iTunes but all related components, reboot, remove the target installation folders and reinstall. For more info, see:

Removing and reinstalling iTunes and other software components