You may need to remove Hyper-V Host without using Credentials if you can no longer access that host. But using SCVMM panel is not a right way sometimes if that host have a associate with another SCVMM server.

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Remove-VMHost -VMHost RH-VOEM01 -Force -Confirm

With using Force switch, you can remove VMHost directly from SCVMM SQL database. So you don’t need credentials because this operation doesn’t remove SCVMM agent on target host. This command saved my life :)