GitHub User administration - mass changes

Question

I'm the organization owner for our GitHub organization under a GitHub Enterprise enviornment.

I need to update the access permissions of nearly 70 users to strip them all down to 'Read' access for all repositories. ( I will need to remove them all in a few weeks)

I'd rather not do this one by one. Is there a way as an Organization owner to set permissions in GitHub to 'Read' for large numbers of selected users across all the repositories/teams they have access to?

I thought about moving them all to Outside Collaborators, but that does not change their existing teams access permissions.

I do not have enterprise admin access, but within the GH organization I have full control of the repositories and organization settings.