I just bought an iPhone 4s and its Apple ID locked?

Its second hand and i'm on the set up section where i'm supposed to enter/creat my Apple ID but its locked to the original owners apple ID and they can't remember their Id or password. I can't use the phone unless I get their account deactivated. Is there any easy way to do this?

You got scammed. The "owners" can't remember the password since the phone is stolen.
Without the Apple ID and password, the phone is about as useless as a brick.

Be smart next time and check PRIOR to buying an iPhone.
Hopefully you didn't pay more than $100 for it.

You should have checked that before paying.

The best way to do it is to contact the previous owner and ask for the information else there's no way to do it. There are a lot of website that claim they are able to unlock it for a fee but most are just scams. You can only unlock via Apple or Apple partners.

The original owner would have to remember/reset the password. Otherwise its a brick.

The others have it right. Now what you do is tell them that one of three things is going to happen. 1. They "remember" the info and get it unlocked for you. 2. They give you back your money and take the phone back. 3. You take it the closest police station and explain the problem and who exactly you got it from. I'll bet you get your money back, or the seller will vanish from the face of the earth.