UPDATE: Alternative method below this one.

OK, so you had a team going and each member created his/her own C5 site and linked it to his/her marketplace account, but you're the team lead and you're supposed to "own" all the projects (alternatively, one of your dev's is leaving and you need to take ownership of the project s/he is working on). So how are you going to do this?

1. You're going to need to get the credentials for the account to want to move the project from - alternatively (preferably), you need to collaborate with that dev. to do this.
2. In the account you're moving the project from, go to the 'My Account' page.
3. In the 'My Account' page click on the 'Projects' link.
4. Click on the project you are changing ownership for.
5. In the 'Management Team' section, there's an edit box under a title 'Add User to Management Team' - enter your account name (i.e. the account you want to move the project to and click on the 'Save' button. You will notice that your account is now listed as 'Contributor' in the 'Management Team' listing.
6. Click on the 'Edit Project' link.
7. In the 'Choose New Owner' section of the page, select your new owner account from the dropdown list and click on the 'Change Owner' button. You will be presented with an "Are you sure?" dialog - click "Yes" if you're sure you want to change ownership.

- If you're simply taking ownership but still allowing that dev. to work on the project, then you're done. If, however, your dev is leaving and you need to remove him/her from the project then... 8. Log in as the user that is now the owner. 9. Again, click on the 'My Account' link. 10. Again, click on the 'Projects' link. You will notice that the project is now listed in your list and that you are the owner. 11. Click on the project listed - you will notice that the account you changed ownership from is listed as a contributor. 12. Click on the 'Remove' link for that account - warning there is NO 'Are you sure?' confirmation, so if you're in a big team, make sure you click the correct 'remove' link.

That's it. Rather simple.

EDIT: 2011/09/07

Thanks to TimMorgan, ('phoenixology' from the #concrete5 irc channel, on freenode.net) there's an alternative way to relink a project. This applies if you have no idea what your account password is, or if your team member isn't playing ball.

1. Go into your favourite mysql database administration client and 'edit' the values in the config table.
2. Look for the MARKETPLACE_SITE_TOKEN and MARKETPLACE_SITE_URL_TOKEN key entries and clear their respective value entries.
3. Go to the dashboard for your relevant site and go to 'sitewide settings'.
4. Go to 'speed settings' and click 'Clear Cache'.
5. Now you can go and click the 'Connect to the Community' link again and relink your project to another account.