I have an SPGroup object populated, how can I remove all members from the group, so that essentially I start with a fresh group.
I can't delete and recreate it, so I need a way to work with the existing SharePoint group.
Thanks in advance
Take a look on msdn
But be aware that you change this group for the whole site collection, if you have other site collections those won't be impacted by the modification of this group.
This should remove all the users in the group for CSOM and SSOM.