I found a solution here

Docker native, on Windows, runs in a Hyper-V virtual machine.

Move existing docker VM

I have to move the VM used by docker to the desired location. I did this using the GUI of Hyper-V manager. The VM for docker is called MobyLinuxVM.

• Right-click MobyLinuxVM
• Select Move
• Select desired location

Set location of futures Hyper-V VMs

And to be sure futures VMs of Hyper-V will be stored on my secondary drive, I followed those instructions

In a powershell terminal (destination folders must exist)

SET-VMHOST –computername <computer> –virtualharddiskpath 'D:\Hyper-V_Virtual-Hard_Disks' SET-VMHOST –computername <computer> –virtualmachinepath 'D:\Hyper-V_VMs'