Is it safe to rm /dev/wmi/dell-smbios?

I'm going though the STIG process on a RHEL 7.7 machine and ran across this finding: https://www.stigviewer.com/stig/red_hat_enterprise_linux_7/2018-11-28/finding/V-72039

[root@localhost scripts]# find /dev -context *:device_t:* \( -type c -o -type b \) -printf "%p %Z\n"
/dev/wmi/dell-smbios system_u:object_r:device_t:s0
[root@localhost scripts]# find /dev -context *:unlabeled_t:* \( -type c -o -type b \) -printf "%p %Z\n"
[root@localhost scripts]# rpm -qf /dev/wmi/dell-smbios
file /dev/wmi/dell-smbios is not owned by any package
[root@localhost scripts]# ls -al /dev/wmi/dell-smbios
cr--r--r--. 1 root root 10, 57 May 19 11:29 /dev/wmi/dell-smbios

I am thinking of just deleting the device file but just don't know enough to be safe.

Go ahead and delete it. It's a dev filesystem, not a real file. Linux will either allow you to delete it or it won't, in any case it will reappear after the next reboot.