Unlink ipod from computer

Once they try to sync it it should erase everything and make it able to be authorized to his account.

 

Apple only limits the amount of computers (5) that can be linked to a single iTunes account but you can have as many iDevices as you like. I would recommend doing a full restore to clear all your own data and details and when it is complete and your touch reboots, shows the connect to iTunes screen and your are asked if you want to restore from backup or as a new device just disconnect it. Then the new owner will needs to connect it to his computer and set it up in iTunes to an account of his own.

 

Or that.

 

Apple only limits iTunes Accounts across computers, not iPods, before you ship the ipod just go to Settings/General/Reset/Erase all content and settings