How do I change a user from internal to external?

Hello, 

I created a Hubshare user as internal instead of external.  When I tried to change it in M-Files, I got a message saying that I could not and that I had to do it in Hubshare.  When I go to Hubshare I don't see how to do it.

The main reason for changing this, is that the user has access to the Activities button

and I thought that option was reserved only for admins, but now I see that any internal user can see it.

I hope you can help me.

Irene