Can we change the user licence type from Chatter External to Chatter Free and profile from Chatter External User to Chatter Free User. I accidentally created Chatter External for Chatter Free and I need it to change to chatter free user.
It's not possible to change the license of a user in Salesforce. (But you are able to select a different profile, which uses the same license.)
I suggest to rename the old chatter users to firstname.lastname@example.org .old and create new users.
(Post etc. can be migrated..)
EDIT: Thanks for your comment Ugesh. You are able to deactivate these old users in order to free up and reallocate the licenses. Therefore the licenses aren't wasted. ;-)