Disabling the crash #kernel (and kdump) in #CentOS / #RHEL:
Edit /boot/grub/grub.conf.
On the kernel line, find the text crashkernel= and set it to crashkernel=no.
Do chkconfig kdump off.
Reboot system.
More Info > https://linuxapt.com/blog/disabling-crashkernel-on-centos-7