I brought Apple Watch but previous owner still has email and activation code on it how do I get rid of it

If whoever you bought the watch from isn't capable of removing the watch from their account, you have purchased a totally useless Apple Watch you can never use. Apple will NOT help you and we cannot help you. Only the actual owner who locked the watch can unlock the watch.

This link contains information you can share with the previous owner if you actually know and can reach them --> What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support

If you don't know or can't reach them, recycle the watch responsibly as it's worthless to you or anyone else.

Read this as well --> The All Too Common SAD Reality of Buying … - Apple Community

You'll need to reach out the previous owner, and have them remove it from iCloud.com/find. Please see this: How to remove Activation Lock - Apple Support