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
Huawei P10 review
1995-2015: How technology has changed the world in 20 years
An overview: What leading creative agencies are doing to improve diversity
New iPad, iPhone SE & Red iPhone 7 on sale now
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.