You should be able to "uninstall" xp off your system if you have ticked that option during installation!!!
If you want to install Win98, you will have to format the system and boot from the Win98 disk to install this o/s
Surface Pro 5 News - release date, UK price, features, specs
Gear VR vs. Daydream: Which delivers the best VR experience?
iPad Pro 12.9 vs Surface Pro 5
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.