Does it delete a user on multi-sites simultaneously?

Yes, Share Logins deletes a user on multi-sites simultaneously. The user will be deleted from all remote sites as long as the user name is the same on the connected sites. Suppose a user is registered on all of your sites that are connected using Share Logins and using the same email and username. If he wishes to delete his account from any of the connected sites then it will be deleted from the other sites too.