I had installed opensuse leap with default KDE. A few days back i also installed the XFCE DE. I know that i have the option of selecting the DE of my choice at the login screen, however i want to know if i can completely remove KDE and just stay with XFCE. In YAST >Software management , i clicked on view>patterns and then selected Delete for plasma 5 desktop and KDE desktop environment. I am not sure what happened 
but both plasma 5 desktop and KDE desktop environment now show unchecked, however all packages under them show checked. Can someone please help me with the right way to remove KDE without breaking the system.
Are you tight on disk space?
If not, why bother?
What you removed, were probably the patterns. A pattern is just a small text file, but with a list of depencies and recommends that bring in other software. Removing the pattern just removes the text file.
You can use Yast Software Management and select the āPackage Groupsā view. In that view, click on āUnneeded packagesā. Those are supposed to be packages that you can safely uninstall without causing problems ā or, at least thatās my impression of what that list is. Now that you have removed the KDE patterns, some of the KDE packages probably show up as unneeded.
Thank you nrickert. No,I have no issues with disk space, just that i like to have a clean system :P. But as you said, i will not really bother as far as it is not causing any issues.