If for some reason you are trying to connect Datamolino to Xero and during the process Xero shows you that you cannot choose the Xero Organisation that you wish to connect (because it is already connected), here is what you can do.
Login to Xero to disconnect your Xero organisation from Datamolino
1. Navigate to Organisation Settings
2. Go to "Connected Apps"
3. Find Datamolino and click Disconnect
Now you can go back to Datamolino and initiate the Xero connection from Datamolino.