rhel8 VM parted command

I have an older HP g5 dl 360 sever running ubuntu server 1604.
On top of it I am running KVM and two red hat 8 virtual machines.
When I use parted after a few commands it says if I continue all data will be destroyed.
Would this be because of my server doesn't use UEFI or because I need to
change to gpt table partition and if so, how.
Thanks Guys