Teams PowerShell questions regarding policies

Hey everyone! Me again with some crazy questions- thank you for taking the time to help!

Ok, so for Teams commands that are in the Skype module such as Grant-CsTeamsChannelsPolicy does the user need to have a Skype for Business Online account?  We have some Teams only users that are only online.

Also, is there a way in Powershell to delete a policy without reassigning users out of it first?  For instance, if I have a custom policy can I delete the policy and will users default to the Global (default) policy?  I know if you do it from the admin center it throws an error that you must reassign the users first- we have a ton of users and policies and want the least admin burden to move them all back over to the Global policy.  Any info would be appreciated.  Thank you!