I'm trying to remove certain users from the Tenant Admin User section but the full User list is not appearing, I am assuming it is because these users that are not appearing are Workspace Administrators?
Is there a way I can remove the users from the Tenant Admin section rather than having to remove them from each model?
You can disable users (active or dormant) in Tenant Administration, but you'll need to go to individual models to remove the user. And of course once you remove the user from the model, that user is also removed from the workspace of which the model belongs to.
At least you can use the Tenant Administration to view all models/ workspaces of which your user of interest belongs to.
Regarding your question of why you don't see the full user list in the Tenant Administration, a user can only belong to 1 Tenant, so perhaps the user of interest belongs to a different Tenant. I would suggest that you email firstname.lastname@example.org to verify that.
Since this is not something i can easily test, i believe disabling users prevents the disabled user from logging into Anaplan, but it doesn't stop a Workspace Admin from deleting the disabled user from the relevant workspace/models, i.e. you need not reactivate the disabled users prior to deleting them.
Do let us know if you manage to do a test with your users.