Cannot run VM in VMWare on Windows 10 due to Hyper-V

I had the same issue. Removing and disabling Hyper-V did not help. Turns out the problem was related to Device Guard (I have Windows 10 Enterprise). I found the answer here. But the gist of it is:

1. Download the Device Guard and Credential Guard hardware readiness tool

2. Run the tool in powershell with the correct execution policy):

   DG_Readiness_Tool_v3.2.ps1 -disable
   

3. Reboot

4. Make sure you have Hyper-V uninstalled and disabled:

   Disable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All
   bcdedit /set hypervisorlaunchtype off
   

Windows 10 should have an option in the boot configuration data which determines whether Hyper-V starts during Windows startup (there is in Windows 8.1). So to disable Hyper-V from starting, in an administrator command prompt you type: bcdedit /set hypervisorlaunchtype off and reboot the computer. After that you can run VMs in Workstation.

To turn Hyper-V back on again, type in an administrator command prompt: bcdedit /set hypervisorlaunchtype auto and reboot the computer. (Source)

The solution to this problem is just disabling Device Guard. Below I show you how to disable it:

1. Open gpedit.msc

2. Go to Computer Configuration → Administrative Templates → System → Device Guard. On the right side double click to edit the properties of "Turn On Virtualization Based Security". Set the setting to "Disabled".

3. Open cmd as administrator and type the below commands:

   mountvol X: /s
   copy %WINDIR%\System32\SecConfig.efi X:\EFI\Microsoft\Boot\SecConfig.efi /Y
   bcdedit /create {0cb3b571-2f2e-4343-a879-d86a476d7215} /d "DebugTool" /application osloader
   bcdedit /set {0cb3b571-2f2e-4343-a879-d86a476d7215} path "\EFI\Microsoft\Boot\SecConfig.efi"
   bcdedit /set {bootmgr} bootsequence {0cb3b571-2f2e-4343-a879-d86a476d7215}
   bcdedit /set {0cb3b571-2f2e-4343-a879-d86a476d7215} loadoptions DISABLE-LSA-ISO,DISABLE-VBS
   bcdedit /set {0cb3b571-2f2e-4343-a879-d86a476d7215} device partition=X:
   mountvol X: /d
   

After doing this you have to reboot and approve the changes with F3.

Quote from https://www.reddit.com/r/Windows10/comments/9zqbo0/running_both_hyperv_and_vmware_workstation/:

Hyper-v is a type 1 hypervisor, vmware is type 2. They cannot coexist (on any OS).

However, you can create a second boot entry so you can boot in hyper-v mode or vmware mode.

https://www.hanselman.com/blog/SwitchEasilyBetweenVirtualBoxAndHyperVWithABCDEditBootEntryInWindows81.aspx

C:\>bcdedit /copy {current} /d "No Hyper-V" 
The entry was successfully copied to {ff-23-113-824e-5c5144ea}. 

C:\>bcdedit /set {ff-23-113-824e-5c5144ea} hypervisorlaunchtype off 
The operation completed successfully.