@tarou chabi Thanks for posting in our Q&A. Honestly, I'm not familiar with Powershell and only share some information that I tried in my environment.
For Connect-MSGraph, it seems that there is no disconnet command under "microsoft.graph.intune" module. I used the following two command lines to find if there is any disconnect command, but no commands about disconnect.
get-command -module microsoft.graph.intune
connect-msgraph|get-member
For Connect-MgGraph, it is suggested to install Microsoft.Graph module firstly and then use the command.
https://learn.microsoft.com/en-us/graph/powershell/installation
https://learn.microsoft.com/en-us/graph/powershell/get-started
When you try to run Connect-MgGraph to connect to a tenant after disconnection, it will prompt you to go to a web page to sign in.
Here is the screen shot showing the process:
Hope it will give you some ideas.
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