How do I get rid of activation lock on iPod touch with iOS 11

The iPod you bought on eBay was not properly set up for resale. The iPod is activation locked to the previous owners’s Apple ID. Without the cooperation of that previous owner your iPod is a brick to you. You cannot overcome activation lock. There is no work around. If you can’t get that cooperation then you should contact eBay and try to get your money back. Otherwise please recycle that useless iPod properly and accept your loss.

Contact the seller and have them do the following: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - https://support.apple.com/en-us/HT201351 Assuming no response from the seller, file a claim with eBay. They should make you whole.