Acronis TrueImage Image Restore- aftermath

I just used TI to restore an image from an external drive to a new larger primary drive c: . My old smaller primary drive is disconnected. I would like to reconnect it, delete the partition and use it as a slave drive. What steps do I need to take in order not to make any waves with my now working setup and what software do I need (TI doesn't seem to do the fdisk type stuff). Open source software would be preferred, I don't do this more than once in a blue moon

Thanks for any suggestions.