I rented a virtual server from a hosting provider that uses VMWare as virtualization software. If I remove the initial user from the virtual machine created by the VMWare admin and If I change the SSH configuration to allow only the users that I created on the virtual machine. Can the WMWare admin still access the data on the virtual machine drive?
Yes. They can access all data, including CPU registers and memory content at will, and there's no way you can tell. Any encryption keys can trivially be extracted from a running VM, so even full disk encryption will be of no use against malicious hosts.
If you don't trust your provider, you have to walk away. You can't provide security against the host.