Reset Forgotten OpenVPN Password

I can reach the Azure portal and RDP into the virtual machine that hosts our OpenVPN Access Server, but the web-admin password is long gone. With full administrative rights on the VM I just need clear, step-by-step help to reset that OpenVPN credential so I can get back into the GUI... (Budget: $10 - $30 AUD, Jobs: Azure, Linux, Network Administration, Network Security, OpenVPN, System Admin, Virtual Machines, Windows Server)