Adding user to to administrators group

PowerShell Help
1

I need help with pshell script to add and remove users from Administrators group.

Scenario:

We temporarily grant access to users to built-in administrators group to perform some administrative tasks and remove their access as soon as they are done.

currently, if I have to grant users access to domain B, what I do is , RDP to the domain_B with my domain_A account as Domain_A account is administrative account, open administrators group and add the user to the group.

2

Add-ADGroupMember -Identity “some group” -Members “Some User”

you can do explicit remoting to access AD module for another domain