Save, edit and run the below PS script to rename Windows VM without restart:
$ComputerName = "New Name"
Remove-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" -name "Hostname"
Remove-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" -name "NV Hostname"
New-PSDrive -name HKU -PSProvider "Registry" -Root "HKEY_USERS"
Set-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Control\Computername\Computername" -name "Computername" -value $ComputerName
Set-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Control\Computername\ActiveComputername" -name "Computername" -value $ComputerName
Set-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" -name "Hostname" -value $ComputerName
Set-ItemProperty -path "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters" -name "NV Hostname" -value $ComputerName
Set-ItemProperty -path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" -name "AltDefaultDomainName" -value $ComputerName
Set-ItemProperty -path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" -name "DefaultDomainName" -value $ComputerName
You can edit and use the below bash script for a Linux VM (Ubuntu in this example):
#!/usr/bin/env bash
NEW_HOSTNAME=$1
echo $NEW_HOSTNAME > /proc/sys/kernel/hostname
sed -i 's/127.0.1.1.*/127.0.1.1\t'"$NEW_HOSTNAME"'/g' /etc/hosts
echo $NEW_HOSTNAME > /etc/hostname
service hostname start
su $SUDO_USER -c "xauth add $(xauth list | sed 's/^.*\//'"$NEW_HOSTNAME"'\//g' | awk 'NR==1 {sub($1,"\"&\""); print}')"